The invention discloses an inter-node time synchronization method, a wireless sensor network and a node thereof. The method comprises the following steps of receiving a plurality of time synchronization data packets from a parent node, wherein the time synchronization data packets comprise a global time t1 when the parent node sends the time synchronization data packets; obtaining a local time t2 of a subnode corresponding to each global time t1, so as to obtain a plurality of groups of mapping data between the local time t2 and the corresponding global time t1; according to a preset fitting rule, fitting the multiple groups of mapping data, so as to obtain a function relationship t1=f(t2) which uses the local time t2 as an independent variable and the global time t1 as a dependent variable. The method has the advantage that the time synchronization of multiple nodes in the wireless sensor network can be accurately realized.