The invention discloses a fluorescein-rhodamine B copper ion ultraviolet molecular probe applied to naked eye detection and synthesizing and using methods thereof, relates to a Cu<2+> probe and synthesis and application thereof and aims at solving the technical problems that an existing Cu<2+> molecular probe needs to use an expensive-price high-precision fluorescence spectrophotometer for detection and is prone to being interfered by external environment. A structural formula of the molecular probe disclosed by the invention is shown in a following description. According to a preparation method of the molecular probe, the molecular probe is prepared by the steps of utilizing fluorescein mono-aldehyde and rhodamine B hydrazine to react and utilizing a mixed solvent of methylene dichlorideand methyl alcohol to separate through a column chromatography. A use method of the molecular probe comprises the steps of dissolving the probe in a mixed solution of MeOH and HEPES buffer solution, detecting an added sample to be detected and judging that Cu<2+> is contained if color of the solution is changed into deep pink from light pink; or detecting ultraviolet spectrum absorbance values before and after the sample is added and judging that the sample solution contains the Cu<2+> if the absorbance value is improved when the wavelength is 502 and 553nm. A detection method is simple, quickand visual.