The development of frequency-conversion technology in the infrared region is in urgent need of new excellent infrared nonlinear,optical (IR NLO) materials. How to achieve a good balance between laser damage threshold (LDT) and NLO coefficient (d(ij)) for new IR NLO candidates is still a challenge. The combination of the highly electropositive alkali metal (Na) and Zn with cf electronic configuration into crystal structure affords one new IR d(10) material, Na2ZnGe2S6. It exhibits excellent properties including a wide transparent region (0.38-22 mu m), large-band gap (3.25 eV), and especially a balance between a strong NLO coefficient (30-fold that of KDP) and a high LDT (6-fold that of AgGaS2), indicating a promising application in the IR region. Moreover, novel common-vertex-linked wavelike (infinity)[GeS3](n) chains are interestingly discovered in Na2ZnGe2S6, which rarely exist in the reported thiogermanides containing alkali metals. In addition,-calculated SHG density and dipole moment demonstrate that the large NLO response is mainly attributed to the cooperative effects of the [GeS4] and [ZnS4] units.