An on‐line emittance–mass scanner (EMS), with a size of 10 cm×10 cm×8 cm, has been developed for use with low energy and light ion beams (A<40) at TRIUMF. Computerized data acquisition and procession give the rms emittances, intensities, and contour plots of each beam component. The angular resolution of the scanner is ±1.0 mrad, the maximum divergence of each component that the scanner can take is 140 mrad. Some experimental results of the measurement are given. The comparison between the contour shapes and the values of the emittance measured by both the emittance scanner and EMS is in good agreement.