The identification of spatial structures of drugs and the researches on their interaction mechanism with DNA are always attractive to the researchers. However, their realization is lack of simple and fast method. This paper reports the establishment of multiple-functional detection platform based on the “turn off-on” model of ZnCdSe quantum dots. In this system, ZnCdSe quantum dots work as the fluorescent probe, platinum anti-cancer drugs as the quencher and triplex DNA as the trapping agent. The seemingly similar cisplatin and transplatin exhibited different fluorescent recovery behaviors due to their difference in structure, and thus realized the selective detection of cisplatin and transplatin with the reaction time set at 10 min as well as the quantitation of cisplatin over the range of 2.5 × 10−8–100 × 10−8M. Based on this, the interactions between platinum anti-cancer drugs and ctDNA as well as polymorphic DNA were further studied, and realized the recognition of triplex DNA. The multiple-functional detection platform integrates the functions of the filtration of high-efficient platinum anti-cancer drugs, the researches on interaction mechanism of drugs, and the recognition of polymorphic DNA, meaningful to the future treatment of viral and cancers based on antisense gene strategy.