the hook length formula for d-complete posets states that the p-partition generating function for them is given by a product in terms of hook lengths. we give a new proof of the hook length formula using q-integrals. the proof is done by a case-by-case analysis consisting of two steps. first, we express the p-partition generating function for each case as a q-integral and then we evaluate the q-integrals. several q-integrals are evaluated using partial fraction expansion identities and others are verified by computer. this is joint work with meesue yoo.