A dense-pitch small-pad copper wire bonded double IC chip stack package comprises a plastic package body, in which a lead frame carrier and a frame lead inner pin are arranged; the upper surface of the lead frame carrier is fixedly connected with a first IC chip; a second IC chip is stacked on the first IC chip; the upper surface of the first IC chip and the upper surface of the second IC chip are respectively provided with a plurality of pads which are arranged as two lines of pad groups in parallel; the two pad groups are respectively a first pad group and a second pad group; a metal ball is implanted on each pad; each metal ball is connected with a first copper bonding ball; and a third copper bonding wire is formed by looping and arching on a corresponding metal ball between the second IC chip and the first IC chip. The preparation process of the present invention comprises thinning, scribing, loading the chip, performing pressure welding, plastic packaging and post-curing, trimming, electroplating, printing, forming and separating, and packaging. The package and the preparation method of the invention avoid the hidden danger of open circuit of a plastic packaging punching wire caused by the crater on the pad, the short circuit of adjacent welding spots, and the easy damage of a previous wire.