Compared to in vitro purified protein complexes, protein complexes in a working state within cells are often more complete, and their three-dimensional structures are in a fully physiological conformation. This is crucial for understanding the structural basis of important functions that protein complexes play in life activities and can also provide more precise target information for drug design. The direct in situ structural analysis of protein complexes within cells is known as in situ structural analysis of proteins, and cryo-electron tomography (cryo-ET) is the key technology for in situ structural analysis. However, cryo-ET has limitations such as low data acquisition throughput for tilt series, cumbersome data processing, and special sample requirements to achieve near-atomic resolution. These issues have become bottlenecks limiting the resolution and practical application of in situ structural analysis. In recent years, a method based on the analysis of non-tilted images has developed rapidly, allowing high-throughput, high-resolution structural analysis of protein complexes within cells. This review will discuss the principles of this method, compare its advantages and disadvantages with traditional tomography, and provide an outlook on in situ structural analysis of proteins. It is hoped that this review will assist structural biologists in better choosing suitable tools.