Objective To investigate osteoclast function levels in children with vitamin D deficiency ricket,and the relationship between the osteoclast function and sex,age. Methods A total of 68 infants and toddlers conformed to the standard were chosen as the case group,and 66 infants and toddlers in good health as the control group.Blood tested 25-hydroxyitamin D[25-(OH)D],tartrate-resistant acid phosphatase isoform 5b (TRACP5b),carboxyterminal cross-linking telopeptide (CTX) levels.Then the datum were analyzed by software SPSS 20.0. Results The levels of serum 25-(OH)D,TRACP5b,CTX concentration for the case group were all lower than the control group and the differences were significant.Between infants and toddlers,the level of serum 25(OH)D for the infants was lower,while the level of TRACP5b and CTX concentration for the toddlers were lower,and the differences were significant.There was no significant difference between different sex in 25-(OH)D,TRACP5b,CTX concentration levels.The serum TRACP5b,CTX had a negative correlation with the serum 25-(OH)D in case group.The correlation between serum TRACP5b and CTX in case group was positive. Conclusions The levels of osteoclast function in vitamin D deficiency ricket children are obviously active;The levels of osteoclast function in infants are more active than the toddlers.There is no big difference for the levels of osteoclast function between different sex in same age group;TRACP5b and CTX are good indexes for evaluating bone resorption.Osteoclast molecule markers will be the promising markers for evaluation of vitamin D deficiency ricket.