Optical spectroscopy of four young radio sources

•The Eddington ratio of young radio source is relative high•The optical properties of young radio sources are similar with those of NLS1s•The broad Hβ of 4C12.50 is the blue wing of the narrow component, not from the BLR

We report the optical spectroscopy of four young radio sources which are observed with the Lijiang 2.4 m telescope. The Eddington ratios of these sources are similar with those of narrow-line Seyfert 1 galaxies (NLS1s). Their Fe ii emission is strong while [O iii] strength is weak. These results confirm the NLS1 features of young radio sources, except that the width of broad Hβ of young radio sources is larger than that of NLS1s. We thus suggest that the young radio sources are the high black hole mass counterparts of steep-spectrum radio-loud NLS1s. In addition, the broad Hβ component of 4C 12.50 is the blue wing of the narrow component, but not from the broad line region.