Since 2003, an active phased array radar at Kamisaibara Space Guard Centre (KSGC) has been used for LEO debris observation in Japan. JAXA evaluated the performance of the KSGC radar at its 10-year anniversary of debris observation. This paper presents the evaluation of detection ability, measurement accuracy and tracking ability, and the improvement of tracking ability of the KSGC radar by tuning parameters. It is well known that the evaluation of the abilities and accuracy are comparatively simple. However, improvement of tracking ability requires know-how that can only be attained through accumulation of observation facts and their analytical results. For example, there are some non-negligible differences between debris tracking and usual flying objects (i.e. airplanes) tracking. Namely, debris tracking can be characterized by the fact that its detective distance is extremely long, velocity is extremely high, fluctuation of relative attitude is unstable, etc. This paper describes the above points, and more specifically, the evaluation method and logic for improving system performance of the KSGC radar by using debris observation data.