Objective To study the diagnosis value of low-dosage spiral CT scanning in the children's pulmonary tuberculosis. Methods 179 children with suspected pulmonary tuberculosis were selected. All the children received the intelligent and automatic tracking based on 80MA-100MA of regular dosage spiral CT scanning. After 2 days, 20MA of low-dosage scanning was applied on children aged from 1 to 7 and 30MA of low dosage scanning was applied on children aged from 8 to 14 years old. Based on the different dosages, CT images were mixed without the milliampere parameters displayed so as to compare the image quality. Results For children aged from 1 to 7, the total score based on the regular dosage was 93.4, based on 20MA of CT scanning, the total score was 74.1 (P ＜0.05), for children aged from 8 to 14, the total score based on the regular dosage was 94.8 scores, based on 30MA of CT scan, the total score was 89.0 (P＞0.05), the diagnosis accuracy rate of two groups were not significantly different (P＞0.05). Conclusion The selection for 30MA of low-dosage spiral CT scanning is applicable to do conventional diagnosis of children with tuberculosis at different ages, the image quality can meet the imaging diagnosis requirements and minimize the radiation dosage. The 20MA of lowdosage spiral CT scanning has a poor image quality and generally don't serve as the conventional diagnosis of children with tuberculosis.