Virginia's Democratic-dominated state legislature today blocked 160 of Republican Gov. John N. Dalton's final appointments, leaving the positions for Democrat Charles S. Robb to fill as soon as he takes office Jan. 16.

The partisan action by the House of Delegates broke a tradition of routine legislative confirmation of gubernatorial appointments that some said is more than 100 years old. All of the appointments blocked today were for state policy and advisory boards, including the state welfare board and the state water control agency.

John T. (Til) Hazel, an influential Fairfax County zoning lawyer and a close friend of Dalton, was one Northern Virginia Republican among the appointees scuttled by the Democrats. Hazel was recently nominated by Dalton to the Virginia Public Building Authority, a prestigious agency that constructs and maintains most state buildings.

"I thought it was the most blatant, partisan move I've seen since I've been in the legislature," said Del. C. Jefferson Stafford of Giles County, one of 25 Republicans in the 100-member House who were unable to block the move. "I hate to see the precedent we are establishing here. I think it shows the direction this legislature is heading."

Some of the boards and commissions affected today, such as the water and welfare boards, wield major political power in the state. Others, like the peanut commission and the Bright Flue-Cured Tobacco Commission have far less influence.

The action came during a special one-day session of the General Assembly that was supposed to be dominated by the House's fourth attempt to approve a redistricting plan to reflect population shifts shown in the 1980 Census. A new plan, which will drastically alter the districts in which most Northern Virginia delegates run, won expected approval today, even though its supporters in the state Senate called the plan deplorable.

The lawmakers also approved a surprise measure that, if signed by Dalton, will delay for a year the auto emission tests that began earlier this month in Northern Virginia. The tests were ordered by the legislature under pressure from the Environmental Protection Agency which threatened to withhold $350 million in federal funds from the state unless Virginia acted to curb air pollution in the Washington area.

"I recently discovered that Maryland and the District are not beginning their emission programs until 1983," said Del. David Brickley (D-Prince William) who introduced the new bill. "Virginia shouldn't be in the position of having to foot the bill alone."

Brickley told his House colleagues that Dalton had promised to keep the bill unsigned while he negotiated with the EPA. If the agency insists that Virginia continue testing or face the loss of funds, Brickley said Dalton will veto the new bill.

"If we ever needed to have a Christmas present or a Hanukah present, this is the time for it," said Brickley.

State officials said today that 11,000 of Northern Virginia's 500,000 motorists have already paid $3.50 to have their automobile exhausts tested at specially designated service stations which have spent a reported $30,000 each to buy equipment for the testing. The testing is required before the state will renew the motorists' license plates.

Several Maryland legislators have filed suit there to block officials from proceeding with plans for the testing.

Under the redistricting plan approved by the assembly, the 18 delegates elected from Fairfax, Arlington and Prince William counties, will be placed in 18 separate districts. If the plan is approved by Dalton and others, the delegates will run from those districts-- instead of multimember ones--in special elections next November.

The state Senate's approval of the plan came begrudingly and with complaints that the plan is aimed at preventing Virginia blacks from winning more than the four seats they now hold in the House.

Sen. L. Douglas Wilder (D-Richmond), the Senate's only black member, castigated the plan. "This is the most blatantly racist bill to come here since redistricting began," said Wilder, who questioned why eight of Virginia's nine largest cities, where 42 percent of the state's blacks live, were in multimember districts while the rest of the state was cut into districts with only one delegate each. "A vote for this is a vote against black people."

Others argued that the Senate had a tradition to uphold -- one of noninterference in the internal affairs of the House. "If we start tampering with the House bill . . . 10 years from now the Senate redistricting will be done by the House," said Sen. Adelard L. Brault (D-Fairfax).

The redistricting plan passed by a vote of 20-13 in the Senate. It still must be signed by Dalton, who vetoed the last plan, then approved by the Justice Department which rejected the first one on the grounds it discriminated against blacks. A federal court rejected the House's second redistricting scheme as unconstitutional. The court has given the assembly until Feb. 1 to come up with a new plan or be redistricted by the court.

Dalton left Richmond today saying only that he will decide next week whether to veto the latest redistricting plan. Civil rights groups promised to continue to challenge the plan at the Justice Department, which must approve it under the 1965 Voting Rights Act.