The invention discloses a micro-fluidic SPR biosensing method and a micro-fluidic SPR biosensing device with high capture ratio and high sensitivity. A micro-fluidic chip technology and a SPR technology are combined, the lower end surface of a microstructural substrate is provided with a three-dimensional microchannel structure consisting of a micropillar array, and the microstructural substrate is sealed with a SPR metal membrane under the microstructural substrate to form a micro-fluidic SPR integrated chip. A micro-fluidic flow field mediated by the three-dimensional microchannel structureis adopted to control the flow direction and the speed of circulating tumor cells (CTC), the contact probability and the combination efficiency of the CTC and the SPR metal membrane are improved on the premise of ensuring the high flux of blood stream, and the metering of the CTC is synchronously realized depending on the high-sensitivity detection capability of SPR to realize the aim of synchronously detecting high-efficiency capture and high sensitivity of a trace amount of the CTC. The method can promote the development of the micro-fluidic chip technology and the innovation of a cell analysis method, push the development of bedside inspection technologies and instruments, is expected to directly utilize a small quantity of blood to implement the screening to high-risk populations, andcan also be used for dynamic monitoring of the treatment effect of cancer patients.