Four novel meta-linked carboline derivatives, two -carboline-based, 1, 3-bis (5H-pyrido[3,2-b]- indol-5-yl)benzene (mCdP) and 2,6-bis(5H-pyrido[3,2-b]indol-5-yl)pyridine (26mCdPy) were synthesized, as well as two -carboline derivatives, 1,3-bis(9H-pyrido[2,3-b]indol-9-yl) benzene (mCaP) and 2,6-bis(9H-pyrido[2,3-b]indol-9-yl)pyridine (26mCaPy) as comparison. The triplet energy of four compounds was higher than 2.70eV, which was enough to be the host materials for FIrpic-doped (2.65eV) blue PhOLEDs. The structure-properties relationship of four host materials was investigated and the efficiencies of blue PhOLED were 42.6cd A(-1), 32.3lm W-1 and 21.4% of external quantum efficiency at 1cd m(-2) for mCaP.