A new power transmission network planning approach employing a plant growth simulation algorithm as the means of optimization is described. The plant growth simulation algorithm is a kind of bionics random algorithm inspired by the growth process of plant phototropism. To assess the potential of the approach proposed， tests are performed on an 18-bus system frequently used in the literature on transmission network planning. As a result， an entire family of interesting solutions have been obtained， including some new schemes not yet reported elsewhere. From the results obtained using this approach， it is concluded that it is a robust and promising technique for this problem by virtue of its simple calculation model， convenient handling of the constraints， and the directional and random search mechanism， which can prevent falling into local optimal point that may appear in previous bionics random algorithms due to uncertainty of some parameters.