Cryo electron tomography (cryoET) is an emerging electron microscopy technique for determining the three dimensional (3D) structures of cellular architectures in their native state at nanometer resolution.While fluorescence light microscopy (FLM) can reveal specific cellular and subcellular targets using fluorescent labels.Combining the advantages of the two techniques, we have developed a method to achieve cryo correlative light and electron microscopy (cryoCLEM) in order to visualize the same sample with cryoET and FLM.We have designed a cryo-stage with which fluorescent images at cryo state (lower than-170 0C) can be acquired.Our design is based on GATAN cryotransfer holder and therefore enables very easy transfer of samples to cryo electron microscope after optical imaging.We have also developed a correlative routine and algorithm with high accuracy and efficiency by using carbon holes on EM finder grids.With this technique, we have successfully imaged synapses in cultured hippocampal neurons and distinguished between excitatory and inhibitory synapses.