Encapsulation, a kind of cellular immune reaction of insect, plays an important role in eliminating foreign objects such as pathogens and parasites which invade insect hemocoels. As a result of limited observation and complicated manipulations, analysis of encapsulation can not be easily performed in vivo. Encapsulation in vitro resolves these problems to a certain extent. Now, encapsulation assays in vitro are usually performed in 96-well plates in which foreign objects such as sephadex beads and insect hemocytes are contained and observed，but some shortcomings exist in this method. In this paper，an improved analysis method on the encapsulation of Ostrinia furnacalis larvae hemocytes in vitro is introduced. 0.2 mL Eppendorf tubes are the substitute for the 96-well plates and they are fixed to a revolving rotator at a speed of 4 circles per min. The states of hemocytes and sephadex beads in insect’s hemocoels are replicated under this method. Results showed that the states of hemocytes were improved and encapsulation was enhanced under the new method and anticoagulants might inhibit the encapsulation ability of hemocytes.