Objective To investigate the aged-related changes of biochemical mark and bone histomorphology in rats and to explore the effects ofαD3 on aged rats. Methods Sixty male Wistar rats with different age were divided into four groups, including group A (6-week-old male wistar rat), group B (6-month-old male wistar rat), group C (24-month-old male wistar rat) and group D (24-month-old male wistar rat +αD3). Group D was treated with αD3 three times per week for 10 weeks at a does of 0.05μg/(kgrameters. The left femur and mandible were collected for histomorphology. Results Compared with group A, ALP (alkaline phosphatase) and BGP in group B, C and D were decreased with age increased [(87.30 ±12.22)mmol/L VS (257.20 ±92.26) mmol/L, (55.23 ± 18. 18 ) mmol/L VS (257.20 ±92. 26) mmol/L,(46.17 ± 16. 6) mmol/L VS (257. 20 ±92. 26 mmol/L); (4. 37 ± 1.46) ng/L VS (9. 03 ±2. 04) ng/L,(3.80±1.00) ng/L VS (9.03 ±2.04) ng/L, (3.59 ±0.64) ng/L VS( 9.03±2.04) ng/L, P <0. 05]. TRACP5b in group C and D increased more than that in group B [( 15.69 ± 1.62 ) pg/L VS ( 7. 26 ±2.13) pg/L, ( 14.16 ± 1.88 ) pg/L VS ( 7. 26 ± 2. 13 ) pg/L, P < 0. 05]. Testosterone decreased significantly with age increased, but no significant difference was found among four groups. Testosterone was positive related with trabecular area of mandible. Bone gla protein was positive related with alkaline phosphatase and negative related with tartrate - resistant acid phosphatase 5b. Trabecular areas of femur increased in group C and D were greater than that in group B[(220310. 6 ±76360. 50) μm2 VS ( 105093.5 ±73242. 2) μm2, (293085.9 ±68230. 78) μm2 VS ( 105093.5 ±73242. 2) μm2, P <0. 05]. Compared with group B,the trabecular thickness of group C was increased by 53%, while trabecular separation was increased 123%. Trabecular area of group D was increased by 33% compared with group C. Conclusions Theresults showed that bone formation was decreased and absorption was increased with age increased. Testosterone was positive related with trabecular area of mandible. Alfacalcidol had the effects to promote the bone mass of mandible.