In the foreground, Chinese workers are busy haresting grain, using tools not much different from those of two millennia ago. In the background looms an enormous mound of earth, a man-made mountain 15 stories high, which contains one of the world's most remarkable archeological treasures: the tomb of Qin Shi Huang Di, the self-proclaimed first emperor of China. In "Xian," an hour-long program which will air on WETA (Channel 26) at 9 tonight, the 1979 grain harvest gets approximately equal time with Emperor Qin, and the result is a rather routine documentary travelogue, rather lacking in focus, with a few segments of absorbing interest.

Qin, who was the first to rule a unified Chinese empire (from 220 to 210 B.C.), reportedly involved some 700,000 laborers in the building of a three-acre "city of the dead" to serve as his tomb and monument. This tomb was rediscovered in 1974 during the digging of a well, and after erecting an enormous roof over the whole site, excavation and restoration began a few years ago. It is barely 10-percent completed, and the full task will take another generation or two, but enough has been unearthed already to give an idea of the staggering richness of the find.

An enormous army of life-size ceramic stgatues -- nearly 7,500 figures distributed through three vaults -- was entombed with the emperor to accompany and protect him in the spirit world, as substitutes for the human sacrifices that would have been made in an earlier century. Qin's tomb lacks the golden glitter of Tut's, but the sheer size of the project, the variety and artistic quality of the figures should make it a comparable tourist attration when the restoraton is completed. Meanwhile, we are offered tantalizing glimpses.

The excavation and the statues are already familiar from some superb photos and rather more thorough discussions in National Geographic and other magazines. The television camera gives them an added dimension, dollying in slowly for a close-up or moving around to show them from more than one side, but the show diffuses its focus. Along with fragments of history, it shows modern Chinese working on farms, jogging, bicycling and doing Tai Chi exercises; it includes rather dull segments on a Buddhist monastery and a mosque, a moderately interesting survey of calligraphy in stone and visits to some interesting but less distinquished tombs. Instead of this smorgasbord, a full hour on Qin and his tomb might have been more interesting and certainly would have been more informative.