Abstract: According to the requirement of practical engineering application,the image reconstruction based on truncated projection is one important problem in X-ray CT.The current local reconstruction algorithms are described and their advantages and disadvantages are analyzed.One local reconstruction algorithm based on improved reconstruction filter is proposed.Via the improvement of the filter,the energy of the filter function is centralized on the center position and its side band falls down quickly to make the filter function have local reconstruction feature.In addition,the improved filter,suppresses the low-frequency information and enhances high-frequency information,can enhance the imaging spatial resolution.While the proposed algorithm enlarges the noise of CT image more or less.The feasibility of the proposed algorithm is validated by the practical experiment data.