Abstract: 9 kinds of fixation fluids were firstly selected from the 18 kinds which were commonly used in biological section-making in zoology in the paper, which are comparatively suitable for the larvae of Lepidoptera. Then through further tests, it was found that: Liquid amount of 30 times to the larvae’s volume was the least consumption of the fixation fluids. 35℃ was the most suitable fixing temperature. The larvae in the fifth age were the best fixing ones. It was the regular best fixing period within 20 minutes after the larva casted off a skin in the fourth age.