The invention discloses a multi-arm machine that can form a double-weaving mouth. The multi-arm machine comprises two rotating shafts and multiple transmission assemblies; each transmission assembly includes one limit piece, two connecting rod elements respectively pivoted on the two rotating shafts, one horizontal rod module with two ends respectively pivoted on the connecting rod elements and one output piece pivoted on the middle part of the horizontal rod module, and the connecting rod elements are controlled and respectively driven by the rotating shafts to move between one distal shaft and one near shaft to drive the horizontal rod module so as to enable the output piece to move reciprocatingly in the depth direction of one guide slot of the limit limit piece and continuously move one comprehensive frame of one comprehensive frame mechanism to one of the top, middle and lower positions, thereby, all the comprehensive frames can be located in the three positions respectively by the aid of the multi-arm machine, so that warp piercing the comprehensive frames respectively can form the double-weaving mouth to achieve the effect of weaving diversification.