Evolution of permeation flux during the ultrafiltration process and variations in sensory characteristics,peptide molecular weight distribution of Aloididae aloidi protein enzymatic hydrolysates before and after ultrafiltration treatment were evaluated in the present study.Moreover,effects of selectivity and separation of ultrafiltration were also studied.Results showed that the sequence of various membranes initial permeation flux was 3 ku>5 ku>10 ku,and their permeation flux decreased gradually with increasing ultrafiltration time.The turbidity and fish odor of hydrolysates were disappeared after 10ku ultrafiltration.With the ultrafiltration of various membranes.The Umami and sweetness of the permeation fraction were significantly increased.There was extensive distribution of peptides with various molecular weight in the hydrolysates,by using only controlled enzymatic hydrolysis hardly enrich the flavor peptides effectively.Permeation fraction comprised mainly of peptides with molecular weight below 3ku and its content was raised to 76.66% from 47.26%.The practical molecular weight cut-off(MWCO) of membrane was larger than the theoretical one,and their gaps increased gradually with decreasing weight cut-off(MWCO) of membranes.