Unsound wheat kernel content is important in the wheat trade and is generally determined by sensory detection. To assist laboratory quality control, inspection personnel training and unsound wheat kernel inspection, visual Certified Reference Materials (CRMs) for unsound wheat kernels were developed. Unsound wheat kernels were collected from wheat fields or laboratory prepared and then screened and embedded in epoxy resin with high light transmittance. The CRMs were developed according to GB 1351-2008, a national wheat standard of the People’s Republic of China. Five CRM items, including injured kernels, spotted kernels, broken kernels, sprouted kernels and mouldy kernels, were developed, and each item contained 10 kernels that demonstrated varying levels of unsoundness. The CRMs possessed excellent homogeneity, and stability monitoring demonstrated that the CRMs were stable at a low temperature of -20? and a high temperature of 45? for 14 days and at least 18 months at room temperature out of direct sunlight and strong light. All the CRMs were assessed by authoritative laboratories and specialists, and the results showed that they conformed to the morphological characteristics described in the textual standard.