Three new monoterpene alkaloids, delavatines C -E (1 -3), along with five known ones (4 -8), were separated from the whole plants of Incarvillea delavayi. All compounds were deduced by interpretation of comprehensive NMR spectral data and X-Ray single crystal diffraction, in combination with a quantum chemical calculation of NMR chemical shift coupled with an advanced statistical procedure DP4 + . Compounds 1-8 were assessed NO suppressive effect in LPS-stimulated BV2 microglia cells. Compounds 2, 3, 6, and 8 exhibited significant inhibition against NO production in LPS-induced BV2 cells with IC 50 values of 25.62, 17.29, 19.94 and 23.88 μM, stronger than or comparable to the positive control (AG) with IC 50 value of 26.13 μM.