Disclosed are an organic small molecular semiconductor material, and a synthetic method therefor. The semiconductor material comprises a diaromatic ring pentalene π-conjugate unit and an aromatic group, and has the following structural formula (I), wherein X1 and X2 are independently selected from O, S or Se; X3 is selected from O, S, Se, NR2, C(R2)2 or Si(R2)2; R2 is selected from a linear or branched alkyl group comprising 1-20 carbon atoms, and a linear or branched modified alkaryl or heterocyclic aryl comprising 7-20 carbon atoms; R1 is selected from a hydrogen atom, a linear or branched alkyl group comprising 1-20 carbon atoms, and a linear or branched modified alkaryl or heterocyclic aryl comprising 7-20 carbon atoms; and A is an electron-withdrawing unit. The semiconductor material can be synthesised by a transition metal catalysed condensation reaction. The semiconductor material of the present invention has a small spectrum band gap, a long spectrum absorption wavelength, a relatively low highest occupied molecular orbital and lowest unoccupied molecular orbital energy level, and can be used as a photoelectric material, especially as a receptor material in an organic photovoltaic device, and it also has advantages such as a simple preparation process, a low cost, etc.