The invention relates to a stainless steel for a heat exchanger welded pipe and a manufacturing method thereof. The stainless steel for the heat exchanger welded pipe comprises the following components in mass by percent: less than or equal to 0.015 percent of C, 0.05-0.30 percent of Si, 0-0.30 percent of MnO, 16.0-23.0 percent of Cr, less than or equal to 0.035 percent of P, less than or equal to 0.003 percent of S, less than or equal to 0.015 percent of N, Ti, 0.03-0.12 percent of Al, Ca, Ni, Cu and O, and the balance of Fe and inevitable impurity, wherein the C and the N are totally less than or equal to 0.025 percent, the Ti is 10 times the total mass of the C and the N or 0.8 percent at most, the Ca is 0.12-0.14 times the mass of the AL, and the Ni, the Cu and the O are totally less than or equal to 0.5 percent. Through reasonable design of type and content of elements, the stainless steel has the characteristics of large heat conductivity, little expansion coefficient, excellentresistance to oxidation, excellent stress corrosion resistance, and the like, and is suitable for manufacturing parts for resisting atmosphere, steam, water and oxidability acid corrosion.