Modal parameters identification algorithm based on continuous wavelet transformation of the Morlet wavelet is an important algorithm in fault diagnosis and multi-modal parameters identification area. However, on the time-scale image of wavelet continuous transformation of the Morlet wavelet, there will appear aliasing phenomenon between two modals while vibration modals are concentrated, and it is hard to separate these concentrated modals. A new wavelet function called modal quasi-wavelet is proposed in this paper. The continuous transformation of modal quasi-wavelet can split two concentrated modals effectively. And the new algorithm of modal parameters identification is put forward. Numerous experiments of the new algorithm indicate that the modal quasi-wavelet shows better performance than Morlet wavelet. The proposed method provides a new approach for concentrated modal parameters identification.