Abstract: Insect has become the most diverse and widely distributed group in the animal kingdom.Reproduction is an important way for insects to ensure the continuation and prosperity of the population.Due to its strong reproductive ability and special reproductive system, female insects can store sperm obtained from males during mating through the organ of spermatheca.The females can delay the fertilization of eggs and control their fertilization time so as to avoid time and environment that are not conducive to the survival of their offspring.After finding a suitable environment and host, the flow of semen will be controlled to fertilize the eggs to ensure the hatching rate of the eggs and the survival rate of the larvae.Reproductive fitness is an important index to measure insect adaptation to nature.In nature, insects usually adjust and adapt to the changes of external adverse environmental factors and their own factors by changing the way of reproductive fitness.Based on the results of a large number of studies on insect reproduction behavior by domestic and foreign scholars in recent years, this article reviews the reproductive fitness of insects from two aspects: environmental factors and insects'own factors.This paper discusses the influences of external environmental factors in aspects of temperature, humidity, light, food and density, and the change of insects'own factors in aspects of body size, multiple mating, mating experience and delayed mating on its reproductive fitness and the application of the corresponding research results in practical production.In addition, it also points out the problems of the current researches in order to provide directions for related further researches and provide ideas for finding new pest control measures in the field.