Abstract: In order to measure the beam emittance which is space charge dominated, a slit-based emittance measurement system is applied in Hefei Light Source(HLS). Two types of slit masks are chosen: multi-slit one and single-slit one. Measurement results show that, single-slit based emittance measurement yields closer results to the simulation value. Moreover, single-slit based emittance measurement can avoid the overlapping between adjacent beamlets, which makes its application range wider than multi-slit technique. The experiment result shows that with the beam charge of 240 pC, normalized emittance of (1.840.085) mmmrad can be achieved at HLS.