[Objectives]  To understand the potential for using Semidalis aleyrodiformis (Stephens), one of the most important natural enemies of Bemisia tabaci, as a biological control for this pest. [Methods]  Under laboratory conditions of (26±1) ℃, RH=75% and L︰D=14︰10, the functional response of S. aleyrodiformis larvae feeding on B. tabaci eggs and adults was determined. The interference equation of S. aleyrodiformis adults feeding on B. tabaci eggs was also determined. [Results]  Predation of B. tabaci larvae increased with the age of S. aleyrodiformis and was highest for 4th instar larvae. The functional responses of S. aleyrodiformis larvae on B. tabaci eggs and adults conformed to Holling’s TypeⅡequation. Although the efficiency of S. aleyrodiformis searching for B. tabaci eggs gradually increased with age, the treatment time (T_h) decreased. The search efficiency of S. aleyrodiformis gradually decreased with the age of B. tabaci aged and the treatment time increased. The density equation of S. aleyrodiformis was E=0.127 9×P^{－0.317 3} and the interference coefficient (m) was 0.317 3. [Conclusion]  Fourth instar S. aleyrodiformis larvae and adult females have potential as a biological control for B. tabaci.