本文主要欲探討中醫望診與相術在中國中古時期的發展與互動關係。望診做為中醫四診之一，與同為觀察人體的相術，在歷經中古時期的整理與發展之後，於當時人的觀念之中，是成為兩門互不相干的方技之學各自發展，還是有所交流與模仿，是一個值得探討的問題。 本文以中古時期成書的醫籍與相書為核心，分為三大部分進行論述。第一部份，針對望診與相術在操作時機的選擇和人體觀察焦點的說明，指出兩者均以晨間初起，尚未從事各種活動之前，為最佳的觀察時機。其目的是為了避免外在因素的干擾，而得以觀察到人體最自然的狀態。觀察時以面部為主體，尤重人氣色的改變。第二部分，以「五色法」的應用與內涵為主，五色法是基於五行衍生而成的產物，以青、赤、黃、白、黑五色為主，對於五色的要求以有光澤為佳。此外，還針對面色與五官氣色的相互配合，來說明疾病壽夭的判斷結果，其原則建立於五行生剋之上。在第三部份裡，因中古時期的人們基於家族興旺的目的，希望能判斷婚配對象是否具有宜子旺家的命運，這種期望反映到醫籍和相書的撰寫時，便產生出專門說明男女好壞相的篇章。而且為求家族延續，對於預測胎兒性別以轉女為男，或是預知新生嬰兒命運壽夭的方法，也受到醫籍及相書撰述者的重視而收錄書中。 透過上述分析，可知相術和望診乍看之下雖然歸屬於不同的方術範疇。但實際上，由於撰述者的學術背景或是操作者的心得，給予兩種學術交流互動的機會，得以借用彼此的內容來擴充、完善自身的不足之處。

This article attention was centered on the medical and physiognomy books of the middle age in China, it has 3 parts description. The first part is for the patient’s complexion and the physiognomy in operation selection and figure observation; both of them are point out the best time of observation is in the beginning of morning without any activity ago. For the second part, using 5 colors of blue, red, yellow, white and black for the standard to judge the life length and request these 5 colors with gloss is the best. Additional, it also collocate complexion and five senses facial expression to explain the judge result is based on the principle of Five lines engender and overcome. In the third part, the people of middle age for the Family extension reason so they hope their Marriage object have a good fate and this expectation response in the writing for the medical and physiognomy books, and bring the content specialized in good and bad looks for both sexes. Even to forecast embryo sex or the way to forecast neonate destiny and life expectancy, also receives takes seriously from the writer of medical and physiognomy books to enroll in the books.