Through simulating the 6a10 band with a partly resolvable rovibronic contour in the (2+3)PRMPI spectra of B1(nπ*) state in pyridine, the rotational constants in B1(nπ*) state are obtained as follows: A′=0.21670cm-1, B′=0.16758cm-1, C′=0.09450cm-1, showing that the negative electricity of N itself becomes weak after one of its lone-pair electrons transits to π* orbital, and the molecular frame expands in general. Moreover, comparing the experimentally measured band with the theoretical curve of 6a10, two vibronic bands, 17a106a101210 and 11b10, which are drowned under the high intensity of 6a10 and have never been reported before, are found.