Because the optical signal has the characteristics of chaotic signal obviously in laser welding, such as large number of mixed information, complex changing in the time domain and the frequency domain, fluctuation violently of random signals, and so on, it is difficult to separate the characteristic information of penetration by conventional means in laser welding. So, according to the distribution characteristics of complex mixed signals extracted from spectral perspective imaging, a new chaotic signal analytical method for high power solid state laser welding is proposed in this paper, which bases on the synergistic extraction method for coaxial penetration characteristic signal. The method includes extracting each transient probability density function of the chaotic signal, dynamically forming a series of simplified feature models with trend recognition feature, and establishing compound correlation recognition between the multi-morphological characteristics of the feature models and penetration state. In this paper, three kinds of characteristic parameters and their definitions and mathematical models were introduced in detail, and there are basic value, dispersion degree and distortion rate, which not only can accurately describe the different characteristics of the feature model, but also have much relationship with different penetration states of laser welding, by experiment verifying. For example, the base value characteristic parameter has obvious recognition effect when the weld penetration degree is bigger, but has much fluctuation amplitude when the penetration degree is smaller. The dispersion degree characteristic parameter is only sensitive to the small penetration state test, which can effectively supplement the basic value, but there are some shortcomings in the larger penetration state. The distortion rate characteristic parameter although fluctuates violently near the moderate penetration rate, when the penetration degree of weld is smaller or larger, the characteristic parameter can get better recognition, which the characteristic parameters of the basic value and the dispersion degree can't do. Therefore, in the characteristic parameters of basis value, dispersion degree and distortion rate, there are relationship of complementary and mutual verification. By the composite identification of their characteristic curves, the laser welding penetration state can be detected qualitatively and quantitatively .The experimental results showed that, after the chaotic signal analytical method combined with the coaxial synergistic extraction method, it can realize the multidimensional compound recognition effect of spectroscopy, optics, statistics, abstract analysis, etc, which can enhance the penetration detection ability of high power solid laser welding effectively, and realize reliable on-line identification of penetration.