DELLA proteins works as a repressor and GID1 is the soluble receptor in GA signaling pathways, but currently little is known about interactive sites of GID1DELLA in conifers. we cloned two DELLA proteins (PtDPL; PtRGA) from Pinus tabuliformis named PtDPL and PtRGA. Sequence analysis showed these two DELLA proteins have DELLA and GRAS specific domains and their evolution distance both are between the rice and lycophyte, and they also have GID1DELLA interactive sites Δ17 domain as angiosperm; BiFC proved that Δ17 domain was key sites of interactions between the PtGID1PtDELLA; Without Δ17 domain, PtdplΔ17 and PtrgaΔ17 mutants showed a strong GAinsensitive phenotype compared to wildtype, suggesting that Δ17 domain is the key interactive sites in conifers GID1DELLA interaction. This research provides the basis for GID1DELLA interaction and GA signaling pathways mechanism.