Gas accretion is an important process in the evolution of galaxies, but ithas limited direct observational evidences. In this paper, we report thedetection of a possible ongoing gas accretion event in a Blue Compact Dwarf(BCD) galaxy, MaNGA 8313-1901, observed by the Mapping Nearby Galaxies andApache Point Observatory (MaNGA) program. This galaxy has a distinctoff-centered blue clump to the northeast (the NE clump) that shows lowmetallicity and enhanced star-formation. The kinematics of the gas in the NEclump also seems to be detached from the host BCD galaxy. Together with themetallicity drop of the NE clump, it suggests that the NE clump likely has anexternal origin, such as the gas accretion or galaxy interaction, rather thanan internal origin, such as an \hii~complex in the disk. After removing theunderlying host component, we find that the spectrum of the "pure" clump canmatch very well with a modeled spectrum containing a stellar population of theyoung stars ($\le 7$ Myr) only. This may imply that the galaxy is experiencingan accretion of cold gas, instead of a merger event involving galaxies withsignificant pre-existing old stars. We also find signs of another clump (the SWclump) at the south-west corner of the host galaxy, and the two clumps mayshare the same origin of gas accretion.