Up-conversion luminescence (UCL) materials are of great importance due to their unique optical properties. In particular, the red UCL, falling into the optical transmittance window of biological tissues, can realize deep tissue penetration depth and high-resolution bioimaging. In this work, effective red UCL is achieved in the ternary sulfide by the introduction of Tm3+ or Ho3+ ions into Er3+ doped NaYS2 under 1550 nm excitation. The main emission peak is successfully tuned from green (NaYS2:Er3+) to highly efficient red luminescence (NaYS2:Er3+,Tm3+ and NaYS2:Er3+,Ho3+). The maximum red to green emission intensity ratio (IR/IG) increased by 31 and 80 times, respectively. The lifetime of 4I9/2(Er3+) level decreases significantly from 3432 s (NaYS2:Er3+) down to 636 (NaYS2:Er3+,Tm3+) and 423 s (NaYS2:Er3+,Ho3+), respectively. This is due to the altered energy transfer pathways, resulting in the population of 4F9/2(Er3+). The mechanisms of UCL and energy transfer processes are further supported by fluorescence decay dynamic measurements. The results show the realization of red-emissive UCL in the promising NaYS2 matrix, representing a new type of red UCL phosphors.