Peking has vowed to turn its thousands of quarrelsome railway workers into a "semi-military industrial army" as part of a nationwide effort to get vital ore and food trains running on time.

The pledge came in an official People's Daily commentary today accompanying an announcement that a national conference on railway work had been held in Peking "recently" to consider problems still plaguing the railroads after last year's factional fighting. The 200 delegates met with the Chinese leadership and received "important instructions" from Communist Party Chairman Hua Kuo-feng and Defense Minister Yeh Chien-ying, the New China News Agency said.

The announcement and commentary did not say the army had taken over the national railroad system, which is crucial to a nation with more miles of train track than paved road. But the involvement of Yeh, most senior of the military figures behind Hua, and the bulletin's tough language indicate that Peking intends at the very least to whip faction-ridden rail unions into military shape and tolerate no more disorder.

Already the important Chengchow Railway Bureau has been placed under military control and a new railways minister, veteran official Tuan Chun-yi, has been appointed in Peking.

A Sunday broadcast from Yunnan Province said the local Kunming Railway Bureau had rarely met its production quotas over the last four years and thus hailed Hua's new instructions. But it warned that the bureau's problems were "very far from being washed away and transport was only "improving gradually."

The People's Daily commentary said: "It is necessary to build and display the spirit of revolution plus all-out exertion (and) build the railway men into a semi-military industrial army . . . "

The commentary hinted that some old feuds among rail workers have not been resolved and, as a result, "rail transport is now a weak link in the national economy." This was the fault of the "gang of four," Mao Tse-tung's widow, Chiang Ching, and three other Politburo members purged in October, the commentary said.

The announcements indicated that the purge of party leaders on the wrong side of last year's political battles will be pursued vigorously in the railway bureaus, and the central ministry will try to reassert its once-tenuous authority.

The promotion of Tuan to the railways ministership filled a nearly year-long vacuum at the top of the rail bureaucracy. The previous minister, Wan Li, lost power in April with the fall of his chief patron, former Vice Premier Teng Hsiao-ping. Teng now appears to be returning to favor and Wan, one of Teng's old bridge partners, has, according to some accounts from Peking, been given a new job as head of the Light Industries Ministry. Other sources say Wan returned to favor with the fall of Chiang Ching in October but was too old and too ill to administer the difficult railroads.

Rail workers have been dissatisfied for years with long working hours and a lack of pay increases. Last year the various factions jockeying for influence in the past-Mao era apparently sought to take control of the railways to insure control of the economy, thus precipitating some pitched battles.

Tuan was in charge of the ministry that builds farm equipmetn when he was purged during the Cultural Revolution. Known for his technical expertise, he was rehabilitated in the early 1970s and given a job in the Szechwan provincial government.