A 3D memory array device includes blocks, bit lines, word lines, source lines (SL), complementary metal oxide semiconductors (COMS), and SL sensing amplifiers (SA). Each block includes NAND strings, and each memory cell in the NAND strings stores one or more weights. The bit lines are respectively coupled as signal inputs to string select lines in all blocks. The word lines are respectively coupled to the memory cells, and the word lines in the same layer are as a convolution layer to perform a convolution operation on the inputted signal. Different SL are coupled to all ground select lines in different blocks to independently collect a total current of the NAND strings in each block. The CMOS are disposed under the blocks and coupled to each source line for transferring the total current to each SL SA, and a multiply-accumulate result of each block is outputted via each SL SA.