Based on effective mass approximation and variational method, the actual conduction band binding potential in quantum well is approximated by the triangular potential considering band bending effect. The binding energy, Bohr radius and non-correlation probability of excitons in Cd1-xMnxTe/CdTe quantum wells are discussed and compared with square wells. The change of binding energy with well width and Mn component is given. Results show that the exciton binding energy increases first and then decreases with well width under the triangular potential approximation, which is similar to square well, but obviously smaller than square well. The difference between them increases with the well width and Mn component (barrier height). Correction of band bending should be considered in the research of related issues.