One thousand and eight brown layers aged 1 4 0 days were randomly divided into 7 groupsunder high temperature , which were fed with different diets respectively .The changes of bloodbiochemical parameters and laying rates were examined. The result showed that high protein dietincreased laying rate and blood biochemical parameters changed significantly. The correlations be- tween laying rate and serum chloride and sodium were significant(p<0.05), Those of serum calcium and magnesium with laying rate were mildly positive and mildly negative ,respectively,and blood urea nitrogen and glucose were mildly correlated with laying rate(P<0.05).