In the present study, an integrated system of laser-positioning PIV and water-level measurement is proposed for monitoring surface velocity and water level in the river. Based on the characteristics of laser-positioning technique, it is designed that four laser points of the integrated system are projected in parallel onto the water surface plane such that the projected lights rectangular-arrayed in the plane can be utilized as spatial referenced coordinates to provide the scale of image ortho-rectification in the PIV measurement. In addition, the 5th laser point of the integrated system is projected with a declined angle onto the water surface plane. Through the laser point displacement, it can detect the variation of water level. Therefore, the system can achieve the flow velocity and the water level of the integrated measurement. In this study, the laser-positioning photogrammetry integrated system has been built at the Niudou Bridge, located in Yilan area, to measure the variation of water level and velocity in the regular flow season and flood period during the typhoon Matmo event. Those measurements in the field are employed to validate the proposed system. By comparing with the other reliable measured data, it is shown that the laser positioning and PIV algorithm of the integrated system performing good accuracy. Therefore, it can be concluded that the system can effectively measure the various conditions of high and low flows during floods, and has a great potential of practical application in the field.