Abstract: Space debris created by man's space activities has brought great risks to launch and operation of spacecrafts, especially in the following few years, there will be more and more space activities in the world. So it is necessary to know situation of current space debris environment and predict its development in the future, thus to provide important reference to protection design and operation of spacecrafts and measures of diminishing amount of space debris. An important component of the debris population that is presented in this paper is the debris generated by on-orbit breakup events. It is collision and explosion event that inflames most the increasing rate of the total amount of the space debris. Breakup events include collision and explosion events. Consequently the ability to model different breakup events is a vital part of a long-term debris environment model. In this paper, the orbital evolution of space debris from the spacecraft breakups has been done a through mathematical analysis. A detailed research on the mechanisms of space debris generation, evolution and annihilation from the view point of evolutionary mode is also given. The velocity increments of space debris from spacecraft breakups are presented. Based on the velocity increments, the orbital elements of space debris are gained. Then the cumulative number and orbital distribution of space debris are analyzed due to atmospheric drag perturbation. Finally, the relevant results are gave and compared with the results of CODRM. The results indicate the feasibility of the algorithm.