The invention provides a light absorption coefficient rebuilding method used for biological photoacoustic endoscopic imaging, and belongs to the technical field of medical imaging. According to the technical scheme, the method comprises the steps of firstly according to photoacoustic signals which are collected by an ultrasonic detector and are generated by biological cavity tissue from all angles, rebuilding a measurement value of emergent light absorption energy distribution; then obtaining a theoretical value of the emergent light absorption energy distribution through forward simulation; finally according to the measurement value and theoretical value of the emergent light absorption energy distribution through forward simulation, constructing a target function, and by optimizing the target function, rebuilding space distribution of a tissue light absorption coefficient on the cross section of the cavity. According to the light absorption coefficient rebuilding method used for biological photoacoustic endoscopic imaging, the photoacoustic signal generated by the biological cavity tissue can be utilized to completely rebuild the space distribution of tissue light absorption coefficients on the cross section of the cavity, and accurate and reliable reference information of changes of organism tissue is provided for early diagnosis of diseases.