Abstract: Monitoring pest population density is the key to prediction precision, which has the significant guidance for integrated pest management in agricultural ecosystem. Based on the traditional monitoring technique of pests, the progress of monitoring pest density with modern information technologies was reviewed. The advantages and disadvantages in application of computer vision technology (CVT), acoustic technique，radar and remote sensing technology to estimate the pest population density were analyzed. CVT and sensor will be powerful and potential tools in assessing the pest density. The pathway and main prospects were expounded in automatic acquisition of the data of pest density. Those modern technologies were significant for pest prediction and integrated pest management(IPM) in the future.