We uses a high-resolution (micrometer scale) photoacoustic microscopic imaging system to continuously monitor early-stage tumor angiogenesis in the ear of mice and its response to anti-angiogenesis therapy. Further, a three-dimensional Hessian-matrix-based vascular extraction algorithm is proposed for the quantitative photoacoustic imaging of tumor vessels to improve the tumor vessel extraction accuracy. Subsequently, the morphological changes in various parameters, such as the diameter, density, and tortuosity, of the tumor vessels are quantitatively analyzed. Furthermore, the potential of high-resolution photoacoustic quantitative imaging to study the pathological mechanisms of tumors and other diseases characterized by vascular changes is demonstrated in this study.