Objective: To explore use of three-dimensional ultrasound for predicting spermatogenic function by monitoring testicular volume before and after treatment in patients with idiopathic hypogonadotropic hypogonadism (IHH),and to compare application value with those of changes in sex hormone levels. Methods: A total of 52 male patients with azoospermia due to IHH received micro-pump pulse infusion of gonarelin for 12 weeks in our hospital from January to August 2019 were selected. Patients were divided into 2 groups :spermatogenic groups(15 cases) and non-spermatogenic group (37 cases, including one case of left cryptorchidism). The testicular volume and sex hormones [follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone（T）] levels before and after treatment in the two groups were compared, as well as the semen routine. Results: After 12 weeks of treatment, the overall testicular volume of patients in the spermatogenic group and the non-spermatogenic group increased (P<0.05). The testicular volume before treatment and the increase of serum T level after treatment in the spermatogenic group were higher than those in the non-spermatogenic group (P<0.05). In both spermatogenic group and the non-spermatogenic group, the increase in testicular volume after treatment was positively correlated with the increase in T level (P<0.05), and was not related to FSH, LH level increase (P>0.05). The sensitivity of the right and left testicular volume before treatment to predict spermatogenesis after treatment was 93.33% and 99.8%, and the specificity was 75.68% and 81.08% respectively. The increase in T level before and after treatment for predicting spermatogenesis had a sensitivity of 80% and a specificity of 97.3% after treatment. Conclusions: Testicular volume monitoring with three-dimensional ultrasound before treatment is helpful to predict spermatogenesis in male patients with azoospermia, and sensitivity of which is higher than that of increase in T after treament.