In order to fulfil the requirement of low area specific resistance and highly stable cathode contact material in planar type solid oxide fuel cell (SOFC) stack assembling, this work investigated the electrical property evolution of LaNi_0.6Fe_0.4O₃ (LNF) with manipulated particle size and its effect on SOFC electrochemical performance. The optimized pre-treatment strategies of LNF were obtained with decreasing ASR, improving SOFC single cell performance and thermal cycling stability. Results show that, the dry-pressed LNF-2 and the high-temperature sintering-pre-treated LNF-3 possess smaller area specific resistances of 0.074 and 0.076 Ω·cm², respectively, more stable particle sizes with shorter conditioning state and faster transfer into steady state after applying 1 A/cm² current load at 750 ℃. Specifically, the single cell with LNF-2 shows improved peak power density of 0.94 W/cm² compared to 0.66 W/cm² of LNF without treatment at 750 ℃. However, it exhibits significant performance degradation during thermal cycling, decreasing by 20%. In contrast, the peak power density of LNF-3 single cell decreases by only 4% after 20 thermal cycles. This work is expected to provide guideline and valued reference for reliable SOFC stack assembling and stable operation.