he lattice parameter c values of highly textured YBCO thick films were calculated by using an X-ray diffraction dual-line method. The lattice parameter values of samples prepared on Ni substrate rather smaller than those of sintered samples and thick films prepared on Ag-Pd substrate. Increasing substrate temperature during spray, sintering temperature after spray, and moving speed of smsples during zone melting makes lattice Parameter c decrease. Generally, the samples which have higher To have rather smaller lattice parameter c values.