Abstract: The thin films of soluble tetra-（tert-butyl）-5, 10, 15, 20- tetraazaporphyrin lead（Ⅱ）（PbTAP（t-Bu）₄） were fabricated by spin-coating technique. IR spectra, electronic spectra, gas sensing of the spin-coating film were investigated. There are strong B-absorption band in ultraviolet region and Q-absorption band in visible region. The absorption peak of thin film shifts to the red and broad compared to solution. The spin-coating film of PbTAP（t-Bu）₄ has better gas sensing to NH₃. The selectivity of PbTAP（t-Bu）₄ spin-coating film was compared on the sensitivity and ability of response-recovery to NH₃ and NO₂. The sensitivity of NH₃ is approximately 12 fold higher than that of NO₂, and the reversibility of NH₃ is better than that of NO₂.