A controllable fractal generation method is put forward based on FBM constraint model. According to the probability distribution of local deformation energy, the FBM constraint model is set up to keep the statistic self-similarity in detail and the controllability in macrostructure at the same time. And the constraint coefficient of the model can be calculated with the threshold estimation. The regional buffering control and regional harmonic control further enrich the control ways during the fractal generation. The controllable fractal generation examples prove the feasibility, validity and the practicality in nature simulation and engineering visualization.