The invention discloses an experimental simulation device for mining hydrate based on multi-branch hole technology, which comprises a multi-branch hole mining unit, a temperature control unit, a gas injection unit, a liquid injection unit, an outlet separating and metering unit, a gas recovery unit and a data acquisiting and processing unit, the data acquisiting unit acquires relevant data of thetemperature control unit, gas injection unit and liquid injection unit and the like, and achieves the control of the temperature control unit, gas injection unit and liquid injection unit; multi layers of horizontal branch holes are arranged around through tapping at the lateral side of a central main well net, the horizontal branch holes are driven by the central main well net to jointly reduce the pressure for hydrate exploitation, the design form of the multi-branch holes is utilized to effectively increase the discharge area of the hydrate reservoir, and can completely simulate the formation of the hydrate reservoir, the layout of multi-branch holes, the pressure reduction of the multi-branch holes, the sand prevention and clogging prevention, the separation of gas-water-sand, and other processes, detailed experimental data is provided for detailed understanding of the mining efficiency and production characteristics and the like of the sea water hydrate multi-branch holes, and a theoretical basis for achieving the efficient mining, productivity evaluation, development scheme and process design optimization of the hydrate is provided.