The invention belongs to the technical field of medical detection of cancer cells, and particularly relates to a preparation method of a nanotube array, a method for specially identifying circulatingtumor cells through a dendritic nanotube array and a microfluidic device used for capturing and regulating cancer cells in situ through the nanotube array. The microfluidic device comprises a PDMS module pool, wherein the PDMS module pool comprises a cell culture pool and a microfluidic channel, and substrate film of the dendritic nanotube array is used for partitioning the cell culture pool on the upper layer and the microfluidic channel on the bottom layer; and the two tail ends of the microfluidic channel are provided with input/output ports used for conveying solutions. The preparation method of the dendritic nanotube array, the method for specially identifying the circulating tumor cells through the dendritic nanotube array and the microfluidic device used for capturing and regulatingthe cancer cells in situ through the nanotube array have the advantages that the capture of the cancer cells has high efficiency and strong specificity, antibody molecules identified specially are modified on a dendritic nanotube, the cancer cells are effectively captured and separated from blood, the dendritic nanotube has excellent biological safety for the cells, and the normal function of thecancer cells is not affected.