Hybrid flash storage has become the mainstream storage device in the field of consumer device. However, the academic study on hybrid flash storage is still insufficient. Based on our research activities, practical experience on hybrid storage devices, and state-of-the-art researches, this paper introduces the architecture of hybrid flash memory, the pain points that need to be solved and the relevant research progress. Firstly, this paper introduces and analyses the hybrid flash memory architecture and the corresponding characteristics. Then the experimental results on real hybrid flash memory are shown and the problems of the hybrid flash memory to be solved are exposed. These problems are full into four categories, write characteristics, read characteristics, read/write interference, and volume characteristics. Finally, the latest research progresses of the corresponding problems are introduced. The advantages and disadvantages of each technique are summarized. Additionally, the future development direction is commented.