InAs nanowires with diameters of 7-70 nm and lengths of up to several micrometres were synthesized by a new modified solvothermal method. The x-ray diffraction pattern showed that the InAs nanowires that were prepared had zinc blende and wurtzite structures. A combination of concentration-driven and ligand-aided solution-solid (LSS) growth mechanisms was used to explain the morphology evolution of the InAs nanowires. The preparation method features a low temperature (120-180 degrees C) and economical mass-production and is free of catalyst nanoparticles. It was believed that we have explored a promising path towards the synthesis of other morphology-controllable one-dimensional (1D) III-V group nano-materials. The structural stability of InAs nanowires during annealing was also studied.