Compared to conventional ultrasonic sensors, the flexible piezoresistive film ultrasonic sensor based on nanographene/polyvinylpyrrolidone (GNP/PVP) offers advantages such as light weight, flexibility, wide bandwidth, easy integration, and the ability to conform to curved surfaces, showing great potential in non-destructive testing and structural health monitoring. However, when the piezoresistive film ultrasonic sensor is close to the ultrasonic emission device, instability in the connection between the sensor and the conversion circuit, or inadequate electromagnetic shielding in the testing system, can introduce significant electromagnetic interference. This interference results in strong signal crosstalk, affecting the acquisition of acoustic field information and the quality of ultrasonic signals within the near-field range. To effectively suppress crosstalk signals, this paper employs phase shift and differential amplification compensation methods, as well as an iterative approximation method based on cross-correlation to reconstruct the ultrasonic signals. Experimental results show that signals processed with phase shift and differential amplification compensation methods can effectively remove the crosstalk received by the GNP/PVP piezoresistive film ultrasonic sensor. Additionally, the iterative approximation method based on cross--correlation reduces the variance of the crosstalk signal interval by 99.18%, thereby more effectively suppressing the impact of crosstalk on the ultrasonic signal.