Abstract: The equation mostly used for correlating experimental data is normal polynomial:f(x,t) =c₀(t)+c₁(t)x+c₂(t)x²+…+c_n(t)xⁿ.However correlation with this polynomial is undesirable when the curved surface formed by experimental data is not smooth or the correlating range of correlation is too large.In this paper, a new correlating equation for this purpose is proposed.There are no undetermined coefficients in the new equation. When this new equation is used for correlating different kinds of experimental data (curved surface), smaller errors will always be obtained in comparison with the normal polynomial.