The invention relates to a system and a method for synchronously testing nanofluid heat transfer coefficient and influence rule thereof on the power generation efficiency influence rule of a thermoelectric generation system. The system mainly comprises a liquid storage tank, a peristaltic pump, a cold water bath, a copper pipe, a heat sink, a thermoelectric device, a heat source, a plurality of groups of thermocouples, a data acquirer, a computer control terminal and the like. The method comprises the following steps: measuring the temperature T1, T2 and T3 of nanofluid entering the inlet end of the cold water bath, at the distance away from the inlet end by 20-30cm and in the cold water bath, calculating the intensified convection heat transfer performance of the nanofluid according to constant-temperature boundary conditions. Heat carried by the nanofluid is estimated by distributing the thermocouples on the heat sink from top to bottom, and the thermoelectric conversation efficiency under differnet nanofluid working conditions can be obtained by combining the conversation power of the thermoelectric devices. The synchronous testing on the intensified heat transfer coefficient of nanofluid under different working conditions, and the influence of the intensified heat transfer coefficient of nanofluid under different working conditions on the cooling effect of the cold end of the thermoelectric devices as well as the influence on the conversation efficiency can be realized, the measurement errors can be decreased, and the testing accuracy can be improved.