Picea balfouriana in Machangliang Forest Farm was observed to discuss its physiological and biochemistry change regulations when infected with needle cast. Three sample plots were selected in the farm and the disease was investigated. The needles were classified into four grades based on the disease level. One-year-old needles were collected at each disease degree to measure the physiological and biochemical indexes. The results show that the disease is more serious at higher altitude region. And the activities of POD, PPO, PAL and the concentration of MDA were high in more seriously diseased needles, but the concentration of chlorophyll b and chlorophyll a+b were low.