本文提出了测量断口分维的一种变分辨率码尺方法，并利用ＷｅｉｅｒｓｔｒａｓＭａｎｄｅｌｂｒｏｔ理论分形曲线对变分辨率码尺方法与传统的变码尺方法进行了对比。结果表明，变分辨率码尺方法优于传统的变码尺方法。用扫描隧道显微镜（ＳＴＭ）利用变分辨率码尺方法在纳米尺度测定了Ｔｉ３ＡｌＴｉ２４Ａｌ１１Ｎｂ合金断口的分形维数。发现断裂表面在纳米尺度上存在分形结构，但不同断裂方向的分形维数不同：Ｔｉ２４Ａｌ１１Ｎｂ合金的分形维数高于Ｔｉ３Ａｌ合金的分形维数 In this paper, we propose a variable-resolution code-ruler method to measure fractal dimensions of fractures. The fractal curves of WeierstrasMandelbrot theory are compared with those of the traditional variable-displacement ruler method. The results show that the variable resolution code ruler method is superior to the traditional variable ruler method. Fractal dimension of fracture of Ti3AlTi24Al11Nb alloy was measured by scanning tunneling microscope (STM) with variable resolution code ruler at nanoscale. It is found that the fracture surface has a fractal structure at the nanoscale, but different fracture directions have different fractal dimensions: the fractal dimension of Ti24Al11Nb alloy is higher than the fractal dimension of TiAl alloy