Through the investigation of Palacmom modestus (Heller) in Taihu Lake, we explored the resource alternation and food com posit iun of shrimp. The shrimp resources decreased rapidly with the increase of ice-fish resources. Its catching yield reduced from 231 0.90 ton in 1975 to 156.25 ton in 1992. The shrimp was omniovorus and had no distinct selection to zooplankton. The residues of zooplankton in the shrimp stomach are similar to the dominant populations of zooplankton in the lake. We also cultured the shrimp larvae hatched in labolratory and studied their growths reproduction and quantitative assay of feeding, 2.7 percent of the larvae which were cultured 2.5 months and hatched in June or July might reach to their biological minimal form and others reached to their biological minimal form at eleven-month-age in May next year, and bore eggs in the second time at 1 A. 5-month-age, but the egg number was clearly less than the first time. Parent shrimps died continuously after their larvae hatched. It is proved indirectly that the age of the shrimp was about fifteen monthes through culture in two times' egg-laying of the same repruduction population. By means uf labolratory experiment, we also conclude that the feed rate of the shrimp was 30.82, and the food efficient change 3.25 percent.