Generally, the well shielded f orbitals made the f-f transition of lanthanides be non-tunable and sharp lines. In the work, the spectral property of Nd3+:SrF2 crystal codoped with R3+ (R3+ = Y3+, La3+, Gd3+) were investigated. The results show that with no loss of crystal structure integrity, the photoluminescence were tuned by the codopants in large scale, and altered significantly with the codopant species and concentrations, which strongly indicates that the f-f transitions could be modulated and tuned rather than the general considerations, and the codopants prefer to work as local lattice structure regulators. At the viewpoint, the designing of new lanthanide-doped laser crystals through the local structure modulation was suggested. With help of the codopant, a quasi-single-center system of Nd3+,Y3+:SrF2 and Nd3+,Gd3+:SrF2 were obtained, and the peak emission cross section, lifetime, linewidth and quantum yields were manipulated to be about 5 × 10−20 cm2, 350 μs, 20 nm and 90%, respectively. The highly improved CW lasing efficiency and output power agreed well with the spectral properties. The modified photoluminescence parameters show that Nd3+,R3+:SrF2 crystal with high thermal conductivity were very promising candidate for generation of high repetition rate ultrashort 1 μm lasers.