Objectives To observe the plasma levels of 25(OH)D and 1,25(OH)2D in patients with chronic kidney disease (CKD) at stages 3～5 and without dialysis, and to explore the association between 25(OH)D and 1,25(OH)2D levels and the factors affecting the levels. Methods Serum 25(OH)D and 1,25(OH)2D were detected by radioimmunoassay. Serum calcium, phosphorous, alkaline phosphatase, creatinine, albumin, hepatic function parameters, glucose were measured by an automatic biochemical analyzer. The association between 25(OH)D and 1,25(OH)2D levels and the factors affecting the levels were assayed by correlation analyses. The independent factors relating to 25(OH)D level and 1,25(OH)2D level were estimated by multiple linear regression analyses. Results Eighty-two CKD patients at stage 3～5 and without dialysis were enrolled in this study. Their average level of 25(OH)D level was 8.81ng/ml (0.34-37.69ng/ml) and 1,25(OH)2D was 17.14pg/ml (1.10-65.40pg/ml). The prevalence of 25(OH)D insufficiency and deficiency were 15.0% and 81.3%, respectively, and that of 1,25(OH)2D deficiency was 44.0%. In patients at different stages, discrepancies in serum level and deficiency prevalence were insignificant to 25(OH)D (P=0.903; X2＝0.343, P＝0.842), but were statistically significant to 1,25(OH)2D (P=0.000; X2＝20.384, P＝0.000). Pearson’s correlation analyses revealed that serum albumin and 24h urine protein positively correlated with serum 25(OH)D, eGFR positively correlated with serum 1,25(OH)2D, and diabetes and serum phosphorous negatively correlated with serum 1,25(OH)2D. Multiple linear regression analyses demonstrated that serum albumin was the independent factor affecting serum 25(OH)D level, and serum 25(OH)D and eGFR were the independent factors affecting serum 1,25(OH)2D level. Conclusions 25(OH)D and 1,25(OH)2D deficiencies were frequently found in CKD patients at stages 3～5. Serum 25(OH)D correlated significantly with serum 1,25(OH)2D. Serum albumin was the predictor for 25(OH)D level. Serum 25(OH)D and eGFR were the independent factors affecting serum 1,25(OH)2D.