海道測量是測量海河江湖等水域的深度、底質、淺灘、暗礁，以及沿岸地帶與海島地形地貌的技術，再將測得資料製成航海圖與航行指南。海測後製成的海圖除了供航海者使用，保障航行安全之外，也是海軍佈置防務的重要依據，對民國時期的中國而言，更是政府掌握領海界線，對外盡海戰時中立國之義務、應付漁權糾紛的憑藉。中國自1880年代以來不乏有籌建海測機構的構想，但囿於財政問題，不是未能實行，就是開辦後成效不彰，直至海道測量局於1921年成立後，中國才有名實相符的海測機關。目前學界對海道測量局的認識，多見於民國海軍通史著作，以簡短篇幅敘述該局成立目的、職掌與編制，迄今未有專文討論。本文主要運用中央研究院近代史研究所藏的《外交檔案》、檔案管理局所藏的《國防部史政編譯局》檔案與相關報刊資料，探討海道測量局的成立緣起、籌備過程、沿革、初期的測量工作與海圖的繪製。

The job of Hydrographic office is to survey and map hydrographic features, and then use hydrological data to publish marine chart and sailing directions. Starting from the eighteenth century, several Western nations established their own hydrographic offices. The major reason was that having self-made chart helped to demarcate maritime territorial boundaries, deploy naval fleets and arms, resolve diplomatic dispute of fishing rights, and fulfill rights and duties of neutral powers in maritime war. So it is important for a nation to develop hydrological work, especially for Republican China. However, China did not have its own hydrographic office until the Hydrographic Department of the Chinese Navy was established in 1921. This is the first office that enabled China to survey and map hydrographic features by itself. But so far, the Hydrographic Department of the Chinese Navy has not drawn much scholarly attention. To study the Hydrographic Department of the Chinese Navy, this article focuses on the founding background, planning, developing and the outcome of its work in the early stage. This article utilizes materials from two main archives: the Diplomatic Archives collected in the Institute of Modern History at Academia Sinica, and the R.O.C Army Archives collected in the National Archives Administration. This article aims to serve as a preliminary study of the Hydrographic Department of the Chinese Navy.