A jet propulsion construction toy assembly includes a container mounted on a movable brick assembly. A launching unit includes a launching seat permitting extension of a nozzle of the container thereinto and having an inlet. When the nozzle extends into the launching seat, an actuator mounted movably in said launching seat is operable to engage the nozzle such that said container is filled with fluid including air and liquid and pumped out of a barrel by a pump through first and second conduits, the inlet and the nozzle. Thereafter, when the nozzle is released from the launching seat due to disengagement between the nozzle and the actuator, jet of the fluid from the container through the nozzle forms a propulsion force to drive movement of a combination of the brick assembly and the container away from the launching unit.