An approach to path planning of the multiple underwater gliders for ocean sampling is presented based on the optimization criterion of sampling time. Firstly, according to the number of the gliders, the path planning problem of the multiple underwater gliders is transformed into a single glider path planning problem by the spatial clustering algorithm. Secondly, the two-step CLK (chained Lin-Kernighan) algorithm is applied to optimizing the sampling path in each sampling subspace. A diffusion algorithm is designed to adjust the sampling points among the sampling subspaces, which minimizes the sampling time of the whole sampling mission. Finally, taking the Sea-wing underwater glider as an example, the simulation experiments are carried out to verify the proposed methods. The results show that the methods can efficiently reduce the sampling time spent on the sampling task.