Objective To study the applied value of the improved pyelographic technique under PACS system.Methods The pyelography in 200 cases(including the traditional pyelography in 92,the traditional big dose pyelography in 8 and the improved pyelography in 100) were retrospectively analysed in groups.Results The improved pyelography in comparison with the traditional pyelography,compressing time reduced 9~11 minute during radiography and the contrast medium amount was the same in both.Conclusion The improved pyelography is superior to the traditional or the traditional big dose pyelography.