By combining theoretical derivation with experimental study, the method of determining starting pressure gradient for low permeability heterogeneous sandstone oil reservoir was established. Firstly, based on the similar principles of reservoir flow field and electric field, equation applied to calculating starting pressure gradient for heterogeneous sandstone reservoir was derived. Secondly, based on steady flow test technique, testing method applied to acquiring starting pressure gradient for heterogeneous sandstone reservoir was established. The results show that determining starting pressure gradient of low permeability heterogeneous sandstone reservoir follows the two equivalent principle. The starting pressure gradient for horizontal heterogeneous reservoir is equal to the weighted average of the starting pressure gradient on length. The starting pressure gradient for vertical heterogeneous reservoir is equal to the weighted average of the starting pressure gradient on the product of permeability and flowing area. The results can effectively guide the determination of reasonable well space and promote the efficient development for low permeability heterogeneous sandstone reservoir.