We investigate the properties of a one-dimensional Bose–Fermi mixture in a triple-well potential with two equally populated spin components at zero temperature. Based on the coupled equations for a Bose–Fermi mixture, we illustrate the symmetry breaking of the Bose–Fermi mixture with different strengths of interspecies and intraspecies interactions that are induced by changing the particle numbers of bosons and fermions. The several novel density profiles of symmetric and asymmetric ground states in the phase diagram of the (NF,NB) plane are demonstrated. In addition, the variation of density as a function of NB at fixed NF, which clearly shows the transition among distinct types of symmetric and asymmetric ground states, is illustrated.