The study investigates the Josephson effect in spin-singlet superconductor/altern magnet/spin-triplet superconductor (SS/AM/TS) junctions using the Green's function method. The current-phase difference (CPR) relationships in these junctions strongly depend on the orientation of the altern magnet (AM) and the types of Cooper pairs. For orientation angles equal to odd multiples of \(\pi/4\), the CPRs follow a \(\sin 2\phi\) pattern, independent of the pairing wave functions in the superconductors. For other orientation angles, the emergence of the lowest-order current becomes possible, with its form depending on the pairing wave functions. The junctions can realize the \(\phi_0\) phase and the \(0-\pi\) transition due to the presence of the lowest-order current. The selection rules for the lowest-order current are presented, and the symmetric relations satisfied by the CPRs are analyzed under mirror reflection, time-reversal, and spin rotation operations. The results provide a method to detect intrinsic spin-triplet superconductivity and have applications in the design of field-free quantum devices.The study investigates the Josephson effect in spin-singlet superconductor/altern magnet/spin-triplet superconductor (SS/AM/TS) junctions using the Green's function method. The current-phase difference (CPR) relationships in these junctions strongly depend on the orientation of the altern magnet (AM) and the types of Cooper pairs. For orientation angles equal to odd multiples of \(\pi/4\), the CPRs follow a \(\sin 2\phi\) pattern, independent of the pairing wave functions in the superconductors. For other orientation angles, the emergence of the lowest-order current becomes possible, with its form depending on the pairing wave functions. The junctions can realize the \(\phi_0\) phase and the \(0-\pi\) transition due to the presence of the lowest-order current. The selection rules for the lowest-order current are presented, and the symmetric relations satisfied by the CPRs are analyzed under mirror reflection, time-reversal, and spin rotation operations. The results provide a method to detect intrinsic spin-triplet superconductivity and have applications in the design of field-free quantum devices.