The definition of the China Geodetic Coordinate System 2000 is identical with that of the International Terrestrial Reference System.The realization of the system is accomplished by two steps.As the first step,the combined adjustment of the Crustal Movement Observation Network of China（CMONC）,the Nationwide GPS First and Second Order Network,the National GPS A and B Order Network,and the Crustal Movement Monitoring Network is carried out in ITRF97,achieving consistent coordinates of some 2 600 GPS geodetic points at epoch 2000.0.As the second step,the velocities of 1 070 CMONC stations are obtained through processing the CMONC data of ten years.Furthermore,the velocities of the remaining 1 500 non-CMONC stations are interpolated using known velocities of the CMONC stations.This paper is devoted to the second step of the realization of the system,namely,to studying the determination of the velocity field in mainland China.The results of the velocity field for the mainland China are presented.Four methods for the utilization of the velocity field are proposed,which are the regional Euler vector method,the local Euler vector method,the grid mean value method and the block Euler vector method.The advantages and disadvantages of individual methods are compared and analyzed in terms of the accuracy of velocity and the convenience of use.A 3°×3° grid mean velocity table for mainland China is appended for user＇s reference.%中国大地坐标系的定义,与国际地球参考系的定义一致。它的实现分两步完成：第一步,通过中国地壳运动观测网络（简称＂网络＂）、全国GPS一、二级网、国家GPS A、B级网和地壳运动监测网等在ITRF97框架内进行联合平差得到约2 600个GPS大地点在历元2000.0的一致坐标;第二步,通过处理＂网络＂的10年观测数据得到该网络1 070个站的速度,并进而用这些站的速度内插出其余约1 500个非‘网络’点的速度。本文致力于实现中国大地坐标系的第二步,即研究中国大陆速度场的确定,给出了中国大陆速度场的结果,提出了
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