Rankine cycle rocket engine system

The invention relates to a Rankine cycle rocket engine system. The system comprises a thrust chamber (1), a condenser (5), a propellant pressurizing unit, an expansion machine (4), a Rankine cycle pressurizing pump (6) and a motor. The propellant pressurizing unit is connected with the thrust chamber (1) and supplies fuel. The thrust chamber (1), the expansion machine (4), the condenser (5) and the Rankine cycle pressurizing pump (6) are connected in series to form a Rankine cycle subsystem. The expansion machine (4) is in transmission connection with the propellant pressurizing unit or is intransmission connection with the propellant pressurizing unit and the Rankine cycle pressurizing pump (6) at the same time. The propellant pressurizing unit and/or the Rankine cycle pressurizing pump(6) are/is connected with a motor for providing additional power. Compared with the prior art, the weight of a battery is reduced greatly, and the system is simple, reliable, easy to control and low in price. 本发明涉及一种朗肯循环火箭发动机系