The invention discloses an iridium tin oxide gradient composite coating electrode. The electrode comprises a pure titanium substrate, a connecting layer, a transition layer and a catalytic layer. Thechemical composition of the connecting layer is IrxSn<0.9-x>Ti0.1O2, x is larger than 0 and smaller than or equal to 0.1, and the thickness is 1-3 micrometers. The chemical composition of the transition layer is IrySn<1-y>O2, y is larger than 0.1 and smaller than or equal to 0.2, and the thickness is 1-4 micrometers. The chemical composition of the catalystic layer is IrzSn<1-z>O2, z is larger than 0.2 and smaller than or equal to 0.4, and the thickness is 8-15 micrometers. The iridium tin oxide gradient composite coating electrode is compact in coating structure and few and small in surface crack, the phase interface of the pure titanium substrate and the catalytic layer can gradually change in a gradient mode through the connecting layer and the transition layer, the bonding strength ishigher, the chemical stability is high, the service life is long, and the problem that in the prior art, an electrode is poor in stability and short in service life is solved.