More than 300,000 copies of the proposed D.C. statehood constitution, printed and mailed at a cost of about $46,000, have begun showing up in the mailboxes of District voters as the campaign over the constitution enters the final week before the Nov. 2 general election.

The citywide mailing of the 10-page newspaper tabloid, which includes the entire text of the 18,000-word document and two pages of arguments for and against it, is part of an $85,000, city-financed campaign to encourage voters to cast ballots on the issue.

The mass mailing to voters was ordered by Congress, which limited the use of the funds to a voter education program that would urge neither passage nor rejection of the document.

Edward Guinan, staff director of the D.C. Statehood Commission that is coordinating the voter education program, said yesterday that the commission also is targeting its $10,000 radio campaign in areas other than Ward 3, where opposition to the document is believed strongest.

"We are playing very heavily to where much of the support for statehood is," Guinan said yesterday. "That is not west of the Rock Creek park."

The ward was the only section of the city to vote against a 1980 citizen initiative that authorized a constitutional convention to draft the documents. The margin of opposition there was more than 3 to 1, while the initiative was approved citywide by a margin of 3 to 2.

If the constitution is approved by the voters next Tuesday it faces almost certain revision by the City Council and Congress, according to many city leaders who view some of its provisions as too controversial.

Critics have cited several of the articles, including provisions that could give police and firefighters the right to strike and could guarantee all city residents a job or adequate income.

The commission has prepared a 30-second radio spot and bought time to broadcast it a total of 120 times on stations WHUR, WWDC, WKYS and WOL, Guinan said. All of the city's radio and television stations have been encouraged to run a separate public service announcement, Guinan added.

In addition to the radio ads, Guinan said, the commission is contracting with private firms for about $1,750 to put up 5,000 blue-and-white posters around the city encouraging voters to go to the polls. Guinan said the posters read, "Vote Statehood Constitution. Nov. 2, 1982." Those posters will be placed throughout the city, Guinan said.

Quarter-page newspaper ads also are appearing in a variety of community newspapers, including the Georgetowner, Washington Afro-American, Hill Rag, Capitol Spotlight, Washington Informer and Washington Blade, he said.