The invention discloses a compound type quaternary ammonium salt cation silicate mineral collecting agent and a preparation method thereof. According to the technology, the method comprises the following steps that 1, any one of alkyl tertiary amine containing carbon 14 to carbon 17 reacts with benzyl chloride or benzyl bromide accounting for, by mass, 45%-55% of the alkyl tertiary amine for 90-150 min under the condition of 90 DEG C-100 DEG C, then is cooled to 40 DEG C-50 DEG C and becomes to light yellow paste; 2, fatty alcohol-polyoxyethylene ether nonionic surfactant containing, by mass, 3%-8% of the alkyl tertiary amine is added; and 3, diesel oil accounting for, by mass, 2%-5% of the alkyl tertiary amine is added and uniformly stirred for 5-20 min at the temperature of 35 DEG C-50 DEG C, and the collecting agent is obtained. The compound type quaternary ammonium salt cation silicate mineral collecting agent has high collecting capacity and excellent selectivity on silicate minerals contained in micro-fine particle iron ore, floatation can be conducted normally within the ore pulp temperature of 5 DEG C-40 DEG C, the pH adaptive range of ore pulp is wide, and the floatation can be conducted normally within the pH range of 5-11.