Objective To evaluate the early diagnostic value of the detection of plasma 1,3-β-D glucan(G test) for deep mycobacterium infection and assess the difference of the G test and fungal culture.Methods We collected test plasma from 420 subjects from January to November 2014,including 226 cases of deep mycobacterium infection,88 cases of non-fungal infection and 106 cases of healthy controls.G-test was used to measure the concentration of 1,3-β-D glucan in the plasma.The cut-off points for 1,3-β-D glucan were determined by using receiver operator characteristics curves(ROC).Results The concentration of 1,3-β-D in plasma of paients with deep mycobacterium infection was significantly higher than that of patients with non-fungalinfection and healthy controls.There was no difference between the control groups.With the analysis of ROC curve,the best cut-off value was 25.33 pg/mL.The sensitivity,specificity,positive predictive value and negative predictive value of G test were 84.9%,70.83%,72.0%,84.1%(P<0.05).Conclusion G Test is a practical and effective method in early diagnosis of deep fungal infection.