The folding transition of model protein chains with various kinds of G (o) over bar -type interactions are investigated by partition function zeros on complex temperature plane. Using multicanonical sampling procedures, the density of states and thus the partition function zeros are precisely obtained. Several factors related to the local distribution of the partition function zeros near the real axis are extracted and used to characterize the features of folding transition. The results show that the folding transition is of first-order-like, and is weakly dependent on the native structures. The efficiency of the method of partition function zero is also illustrated. The correlation between some conventional thermodynamic factors for characterizing the stability and foldability and those obtained from the zeros are also studied. Finally, a mapping between the various models and the G (o) over bar -type models is proposed based on the factors related to zeros, which suggests the wide applicability of the method based on the partition function zeros. (C) 2003 American Institute of Physics.