Abstract: Different Brassica vegetable crops and oil seed Brassica crops were applied to observe the biological parameters of Plutella xylostella under laboratory condition. The larval, pupal duration, pupal mass, percent larval pupating, percent survival to adult and fecundity were recorded. The shortest larval and pupal period was recorded on Brassica camelina and Eurica sativus , and the longest larval and pupal period was recorded on cabbage Brassica oleracea var. capitata and Brassica oleracea var. botrytis . Percent larvae pupating varied significantly, and percent survival to adult stage was also varied significantly. The highest survival rate was found on cauliflower Brassica oleracea var. botrytis . Pupal mass on different host plants varied significantly, the lowest on Brassica napus and the highest was on E. sativus . The highest fecundity was observed on rocked seed fed female. Nitrogen content of different host plant leaves were also varied considerably and had obviously correlative with the pupal mass and the fecundity.