The cumulative and independent yields of various fission products within the mass range of 77–151 have been measured in the ²²⁹Th(n_th, f) reaction by using radiochemical methods together with an off-line γ-ray spectrometric technique. The post-neutron mass chain yields were obtained from the cumulative fission yields by using charge distribution correction. From the mass yields data, the peak-to-valley (P/V) ratio, full width at tenth maximum (FWTM) of light and heavy mass wing, the average light mass (<AL>) and heavy mass (<AH>) as well as the average neutrons number (<ν>) were obtained. The fine structure of mass chain yield distribution (MD) in the ²²⁹Th(n_th, f) reaction was explained from the point of nuclear structure effect such as shell closure proximity and even-odd effect. The MD in the ²²⁹Th(n_th, f) reaction was compared with the MD of ²³⁵U(n_th, f) reaction and the role of standard I and standard II asymmetric mode of fission was examined.