The present application relates to a modular tower-type solar thermal power generation system, which comprises: a solar thermal collector device configured for collecting solar thermal energy, a heat exchanger connected to the solar thermal collector device and configured for producing superheated saturated steam, and a thermal power conversion device connected to the heat exchanger and configured for converting the superheated saturated steam into electrical energy; the solar thermal collector device comprises a plurality of tower-type solar thermal modules. By adopting a solar power generation system with a modular solar energy collector device, the present application can simplify the construction process, reduce the construction period, and can further reduce design cost and investment cost of a power station, as well as improve the efficiency of the heliostat field; moreover, when one of the single towers malfunctions, the working situations of other tower-type solar thermal modules won't be affected, and thus the continuity and stability of power supply using the whole power generation system are ensure.