INTRODUCTION: Polygonum multiflorum Thunb., a widely used herbal medicine, has trouble with the hepatic adverse effect. Processing is an effective method to increase potency and reduce the adverse effects of herbal medicines. Polygoni Multiflori Radix Praeparata (PMRP), the decoction pieces processed from raw material, is widely consumed in clinical practice in many countries. The quality control of PMRP has attracted more and more attention worldwide. OBJECTIVE: A simple and rapid quality evaluation method using an electronic eye (E-eye) combined with chemometrics was proposed for controlling the quality of PMRP. MATERIALS AND METHODS: The semi-quantitative and quantitative data of 105 major components in 128 batches of PMRP samples obtained by three different analysis instruments were fused to investigate the correlation with the dynamic exterior colour determined by E-eye. The correlation between exterior colour and chemical fusion dataset was investigated by orthogonal partial least squares discriminant analysis (OPLS-DA) and partial least squares regression (PLSR). According to the results of correlation analysis, the color parameters of high-quality PMRP was set. RESULTS: Correlation studies by chemometrics revealed that the exterior colour depth was significantly correlated with 32 components [variable importance in the projection (VIP) > 1.0, p < 0.05]. The colour parameter of located in the range of 46.69-51.66 can be used easily, rapidly, and in an environment-friendly way to determine whether the PMRP sample has reached sufficient processing time with good quality. CONCLUSION: This study adds some scientific information to our understanding of traditional medicine while contributing an alternative method for assessing the quality of other decoction pieces.