Boeing Co. said yesterday that its 1980 profits were up 19 percent over the previous year, buoyed by increased sales and growth in defense contracts. Lockheed Corp., meanwhile reported earnings were off 51 percent as a result of high production costs on its L1011 TriStar, high interest rates and reduced demand.

In Seattle, Boeing Chairman T. A. Wilson said the company earned $600.5 million ($6.23 a share) during 1980 compared with $505.4 million ($5.25) in 1979. Revenues were up 16 percent from $8.1 billion in 1979 to $9.4 billion.

Boeing said it had profits of $165.7 million ($1.72) for the fourth quarter compared with $144.6 million ($1.50, adjusted for a 3-for-2 stock split) for the same period of 1979.

At Lockheed's Los Angeles headquarters, Chairman Roy A. Anderson said the company's profits dropped from $56.5 million in 1979, which included an extraordinary tax credit of $20 million, to $27.6 million last year. Per-share earning dropped from $3.56 to $1.53. Revenues were up 33 percent, from $4.1 billion to $5.4 billion.

For the fourth quarter, Lockheed had profits of $25.8 million ($1.68 a share), an 88 percent gain from earnings of $13.7 million (85 cents) for the same period of 1979. Sales rose from $1 billion to $1.5 billion.

Wilson said Boeing's military business reemerged as a growth element in 1980, with the company being selected as prime contractor for the Air Force's cruise missile program and receiving new assignments on the Airborne Warning and Control System.

Boeing's jetliner sales also were up, from 306 in 1979 to 361 last year, Wilson said. Increasing orders for Boeing's new family of fuel-efficient jetliners -- the 757 and 767 -- picked up the slack from a drop in orders for the older 727 and 747, he said. Boeing expects to deliver the first 767s in the third quarter of 1982, with the first 757s out by early 1983.

In Los Angeles, Anderson said Lockheed lost $199 million on production of the L-1011 jumbo jet last year, up from $188 million in 1979.

He attributed much of the loss to production and supplier problems during a speed-up in production in the first half of 1980. Lockheed also lost money late in the year when a reduction in demand forced the company to reduce production from 25 to 18 aircraft a year.

In addition, he said the company's interest expenses increased 47 percent from $72 million in 1979 to $106 million last year.

UAL Inc., parent of United Airlines, says it earned $35.5 million in the fourth-quarter last year and $21 million for all of 1980, attributing the turnaround from 1979's losses to increases in the carrier's average revenue per scheduled revenue passenger mile. A revenue passenger mile is one paying customer flown one mile. Preliminary earnings for the fourth quarter were $1.20 a share, while for all of 1980 profits equaled 70 cents a share.

By contrast, the company had a loss of $12.5 million in the fourth quarter of 1979 and a loss of $72.8 million for all of 1979.

Conoco Inc., the country's ninth-largest oil refiner, said yesterday that it earned $1.026 billion ($9.52 a share) last year, up 24 percent from $815 million ($7.58) in 1979.

Cities Service Corp., the No. 18 oil refiner, also reported an earnings rise for the year to $477.5 million ($5.73 a share) from $347.8 million ($4.18) a year earlier, a 37 percent rise.

Conoco's 1980 sales rose to $18.8 billion from $13.1 billion in 1979.

Fourth-quarter profits were $241 million ($2.23) on revenues of $5.2 billion, up from $191 million ($1.77) a year earlier on revenues of $3.8 billion.

Cities Service reported 1980 sales were $7.79 billion, up from $6.28 billion in 1979.

Fourth-quarter profits were $107.8 million ($1.29) against $106.2 million ($1.28) a year earlier. Revenue was $2.16 billion, up from $1.8 billion.

United Technologies Corp. reported yesterday that it earned $393.3 million ($7.28 a share) last year, up 21 percent from $325.61 million ($6.49) in 1979 on a 36 percent rise in sales to $12.324 billion from $9.053 billion.

The company also announced an increase in the regular quarterly dividend on common stock to 60 cents a share for 55 cents, payable March 10 to holders of record Feb. 20.

Fourth-quarter profits were $102.54 million ($1.89) on sales of $3.545 billion compared with $89.08 million ($1.64) a year earlier on sales of $2.977 billion.