Objective：To investigate the optimal tube current for low-dose high resolution computed tomography（HRCT） scan of pig lung specimen in vitro. Methods： Brightspeed Elite 16 multislice spiral CT from GE company was used to scan five fresh isolated in－flatable lungs of pig by methods of conventional scanning and different low-dose scanning（the tube current of conventional scanning was 200 mAs while the tube currents of low- dose scanning were 80，60，40，20，10 mAs；other scanning parameters were fixed）. Then the quality of the scanning images was evaluated. The quality of images was guaranteed under the premise of meeting the diagnostic requirements and obtaining low-dose volume HRCT technology solution. Effective dose（ED） per scanning was also calculated and analyzed statistically. Results： When the tube currents were 80，60，40 mAs，the radiation doses were lower gradually，with statis－tically significant differences（F=173.90，P<0.001） and the quality of scanning images can meet conventional diagnostic requirements. When the tube current was 20 mAs，the dose of radiation was lower and the quality of the image can basically meet the diagnostic requirements. When the tube current was 10 mAs，the dose of radiation was the lowest，but the quality of image can not meet the diag－nostic requirements. Conclusions：When we chose the tube current of 40 mAs，it can ensure high quality of CT images and reduce the radiation dose at the same time. So it is of significance for clinical doctors to formulate low-dose lung scanning solutions.