Jinping-Sunan ±800 kV UHV DC line uses hydraulic splicing fitting and strain clamp, and the grip strength of fitting should be more than 95 % RTS. Because 900 mm2 large cross-sections ACSR was 4-layer aluminum stranded structure, especially the aluminum/steel ratio of JL/G3A－900/40 conductor was larger, this paper mainly studied the influence factors of fitting on the grip strength of large cross-section conductor. The result shows that there is a wire strength loss caused by crimping, which is the main influence factor, as well as aluminum /steel ratio.