The invention discloses an on-chip scratch-pad memory (SPM) management method facing a multitasking embedded system. The on-chip scratch-pad memory management method comprises the steps as follows: pre-analyzing a program code segment; tracking a program to obtain an internal storage instruction accessing sequence of the program, so as to acquire the accessing times of an internal storage code block and Cache miss information, and accounting and recording a space-time conflict set of the internal storage code block under access of the Cache; selecting an algorithm as required to obtain an optimized SPM distribution scheme; generating a code distribution dispersion loading file, newly mapping and distributing the program code segment, and newly compiling codes to obtain an optimal execution result. Via comprehensive consideration of accessing frequency, cache miss frequency, intertask and intra-task conflict, the required optimal distribution is obtained, the utilization rate of the SPM is maximized, and finally under the premise of ensuring the real-time performance of the program, an optimal execution time scheme or an optimal energy conservation scheme is obtained.