The invention relates to a stainless steel surface treatment 
reagent, in particular to a stainless steel surface colouring method. According to the invention, with water as a 
solvent, each litre of solution contains 30-80g of 
molybdate, 10-18g of 
boric acid, 2-5g of 
zinc sulphate, 0.5-5g of 
manganese sulphate, 2-15g of 
antimony nitrite, 0.2-2g of 
lanthanum nitrite and 0.1-10g of 
sodium malonate. The stainless steel surface colouring method comprises the following basic flow: oil removing, electrolytic 
polishing, cleaning, colouring, cleaning and 
drying and obtaining the finished product, wherein an 
anode is a workpiece to be coloured, a 
cathode is a 
lead plate, a colouring current is controlled to be 0.1-5A / dm<2>, 
voltage is 1.5-2.5V, a colouring temperature is 
room temperature, colouring time is 0.1-30 minutes, cleaning and 
drying are carried out after colouring, and the surface of the obtained sample is uniform and bright. The stainless steel electrochemical colouring process provided by the invention needs simple equipment, is easy to operate, contains no toxic substance and is beneficial to 
environmental protection; and colouring is stable, and a high-quality colour stainless steel product can be produced by adopting the stainless steel electrochemical colouring process.