Aiming at space debris mitigation for small satellite after the end of mission, several approaches are analyzed and compared, and implementations are suggested in this paper. In recent years more and more small satellites have been developed and launched into orbit. Most of them run on Low Earth Orbit (LEO) with height less than 2000km. On the one hand, the small satellites increase the density of space debris and the risk of collision; on the other hand, some of them have orbit lifetime over 25 years if only depending natural attenuation beyond the guideline of Inter-agency Space Debris Coordination Committee (IADC). In this paper several approaches are analyzed and compared for space debris mitigation after the end of mission, including the utilizations of air drag, solar radiation pressure, rocket propulsion, and others. The cost will be required for small satellite to mitigate space debris. For lower orbit small satellites and their constellation, the functions and performances perhaps are degraded. For higher orbit satellites, lifetime of spacecraft always is more than 25 years. Then some supererogatory equipments should be appended to shorten orbit lifetime, such as air chamber, sail, even thruster, usually they are not necessary for small satellites. Based on the analysis of effect and cost for these approaches, implementations are suggested for small satellite with different functions (whether or not provide capability of orbit control) and different mass: 50kg, 100kg, 150kg and 300kg. This research is supported by China National Space Administration (CNSA).