The invention discloses a composite positive ion capturing agent and a preparation method thereof, and can be applied to the technical field of iron ore reverse flotation. The capturing agent comprises the raw materials of lauryl amine and octanol; and the capturing agent is transparent liquid, reaches a freezing point of -18-15 DEG C, and achieves the foaming performance. The preparation method comprises the following steps: the raw materials are mixed according to matching requirements or through a batch dripping mode; and then, the mixture is uniformly stirred to finish preparation. The capturing agent for iron ore reverse flotation can achieve the purposes of saving lauryl amine and improving the iron concentrate grade; octanol is added to enable the capturing agent to achieve the foaming agent performance in the iron ore reverse flotation process, so that the medicament consumption is low, and the flotation effect is good; the capturing agent can be fully dispersed in pulp to facilitate quick collision with minerals, so that the flotability of quartz is reinforced, and the iron concentrate quality is improved; and lauryl amine needs no acidification, and can be directly used by mixing and dissolving with other medicaments to achieve more convenience and environmental protection.