An online magnetic spectrometer system based on a hybrid pixel detector is proposed for the diagnosis of the D³He proton spectrum and yield in laser fusion implosion experiments. By identifying the number and energy of the track clusters and considering the experiment setup, the proton spectrum and yield could be deduced in time. The online diagnosis system is tested on the SG laser facility, in which 31 laser beams are focused on the capsule to drive the fusion reaction. With D₂ and ³He gas mixed 1∶1 by atomic ratio, the primary D³He proton energy spectrum with center energy of 14.6 MeV, FWHM of 2.1 MeV, and yield of 2.3×10⁹ is obtained. This system could provide the D³He proton spectrum and yield online, which would be helpful to improve the experiment in time.