The invention provides a flotation collector, namely a dialkyloxycarbonyl bisthiourea compound. In the structural formula of the collector, R1 represents alkyl, aryl or aralkyl of C1-C8 and R2 represents alkylene of C2-C6. The flotation collector is synthesized through addition reaction of N-alkyloxycarbonyl isothiocyanates and a diamine compound. As the molecules of the collector have a plurality of coordinating atoms and coordinating groups, the dialkyloxycarbonyl bisthiourea compound serves as the flotation collector, which can enhance flotation separation and extraction of nonferrous metal ores and precious metal ores and has the characteristics of high flotation efficiency and metal recovery, etc. The invention also relates to a preparation method of the collector.