A shell-tube type single-spacing-plate refrigeration evaporator with shells being connected in series comprises shells, a front end cover, a front partition plate, spacing plates, a back end cover, aback partition plate and a copper tube. Each shell is a cylindrical cast iron shell. The multiple shells are connected together in series in an end-to-end manner and are sealed. A refrigerant inlet isformed in the side wall of each shell and located at the position being one third below the center line of the side wall of the shell. A refrigerant outlet is located on the top of each shell. The refrigerant inlet and the refrigerant outlet of each shell are far away from each other in the axis direction of the shell. The edges of a bottom shell and a tube shell of the front end cover are provided with bolt holes. The two ends of the spacing plate between every two adjacent shells are welded to the ends of the two corresponding shells correspondingly. The back end cover is formed in the manner that a cylindrical shell on the outer ring and a spherical-surface-shaped bottom cover are welded. The copper tube is arranged in the shells. According to the shell-tube type single-spacing-plate refrigeration evaporator with the shells being connected in series, a refrigerant pipeline is arranged in each independent shell, so that occupied space is reduced, water in the copper tube can be fully utilized to conduct heat exchange, and the heat exchange efficiency is improved.