Abstract: A laboratory study was made on the mating behavior of adult Orthaga achatina and the oviposition behavior of female O. achatina at 28 ℃,75% RH,and 14 L/10D photoperiod in the artificial climate incubator. The adult O. achatina did not mate until the start of scotophase with the mating rate increasing sharply at the 5th hour and reaching the peak at the 6.5th-7th hour of scotophase. The mating rate varied with moth age, being the highest at the age of 2-3 d with a mating rate of 43%.The mating behavior could be divided into two successive periods:premating period and mating period.The mating between female and male O. achatina occurred during the 5th-9th hour of scotophase, with the peak at the 6.5th-7th hour of scotophase. The whole process of oviposition of female O. achatina was done at scotophase. After mating, a little female O. achatina began to lay eggs on the first day, and the female O. achatina entering into oviposition period sharply increased on the second day.The amount of eggs reached the most on the third day and sharply decreased on the fourth day. Moreover, eggs laid on the second and third day amounted to 84% of totality during the whole process. Under the laboratory condition, an egg mass with 2-3 tiers has 47.6 grains averagely. The mating rate between male and female O. achatina and the amount of oviposition of the female O. achatina was curvilinearly related to the moth age obviously.