The invention provides a positioning device and a material transferring system, and relates to the technical field of material positioning. The positioning device and the material transferring systemaim to solve the problems that materials are prone to move in the transferring process, and the transferring efficiency is low. The positioning device comprises a bearing platform, an alignment mechanism and a clamping mechanism, the clamping mechanism comprises a first actuator, a transmission assembly and at least two sets of clamping assemblies, the transmission assembly comprises transmissionwheels and a transmission belt, the actuator is connected to one transmission wheel, each clamping assembly comprises a sliding block and a clamping part, each of the two sides of the transmission belt is connected to at least one sliding block, a through holes are formed in the bearing platform in the first direction, the clamping parts extend out of the through holes, the alignment mechanism comprises a fixing part, a second actuator and a push block, the fixing part and the push block are oppositely arranged in the second direction, and the second actuator is connected to the push block todrive the push block to move in the second direction. According to the positioning device, materials are positioned in the first direction and the second direction through the alignment mechanism andthe clamping mechanism, so that the materials are prevented from moving in the transferring process.