Despite a large number of studies relevant to MX (M = Ti, V, Nb; X = C, N) precipitation in microalloyed steels, the evolution rules of the precipitate morphology remain unclear. In this work, the precipitation behavior and morphological characteristics of MX precipitates in deformed Ti-V-Nb multi-microalloyed steels under contin-uous cooling were revealed through integrating transmission electron microscopy and theoretical models. The experimental results demonstrate that the precipitates are mainly Ti-rich cuboidal multi-component precipitates and irregular compound precipitates formed in austenite, and fine spherical V8C7 precipitates formed in ferrite. For the first time, the L parameter model that evaluates the shape of MX precipitates has been introduced into microalloyed steels, together with the validating experiments. In austenite, as the L increases, precipitates tend to become cuboidal under equilibrium conditions while rod-like elongating along their (100) orientation under deformation conditions; in ferrite, as the L increases, precipitates tend to be disk-like under equilibrium con-ditions while thin elliptical cylindrical extending along their (110) orientation on the habit plane under defor-mation conditions. The evolution rules of precipitate morphology revealed in this work provide insights in controlling precipitates morphology to develop high-performance microalloyed steels.