Polymers with negative charge groups, such as carboxylic or phosphatic groups, were frequently used to induce or promote the apatite deposition. However, chitosan with potentially chelated calcium ions, were ignored. Inspired by layer by layer technology, chitosan hydrogel without any surface modification process was used as framework to mineralize bone-like apatite. XRD and IR results shown that in situ synthesis bone-like apatite, similar to apatite in rib of rabbit, was carbonate ions partially substituted apatite and preferred growth orientation in direction of their c-axis. Bone-like apatite with nano-flake shape with size of 1um fully covered chitosan in short period of time. In case of chelation effect of amino groups, chitosan hydrogel provided heterogeneous apatite nucleation sites, which supported by fact that bone-like apatite tended to deposit on porous wall of chitosan, rather than grow in form of free-standing.