The invention discloses an electrochemical synthesis method for aminophenylarsonic acid. The method uses an inert electrode as an anode, and uses copper, silver, titanium, chromium, nickel, cobalt, palladium, platinum or an alloy electrode thereof as a cathode; the cathode electrolyte contains reactant nitrophenylarsonic acid and supporting electrolyte acid represented by structural formula (A), and is electrified to carry out electrolytic reaction so as to reduce nitro into amino; and after full reaction, an electrolysis product is reclaimed to obtain the aminophenylarsonic acid. In the formula (A), X, Y, Z, E and F are independently selected from H, NO2, OH, Me, MeO, EtO, F or Cl respectively; and at least one of the X, the Y, the Z, the E and the F is the nitro. The electrochemical synthesis method has the advantages of higher yield, lower production cost and environmental friendliness.