A system and a method for monitoring pressure inside a railway vehicle comprise a carriage pressure detection device, a control device, and an alarm device. The control device is configured to receive and process a pressure signal collected by the carriage pressure detection device, perform calculation on and analyze the collected data, and transmit an alarm signal to the alarm device as an alarm when a preset alarm condition is met. When a pressure protection device fails, pressure changes inside the vehicle are monitored in real time by the carriage pressure detection device functioning independently of the pressure protection device.