In order to improve the ability of enhancing image′s edge and texture,the fractional differential operator for frequent domain characteristics is proposed and analyzed.It shows that the fractional differential can greatly increase high frequency component,reinforce medium frequency component and non-linearly preserve low frequency component of the signal,hence they could be used for edge and texture enhancement.Starting from the definition of the fractional differential,an approximate fractional order differential module from which a linear filter is adopted is constructed.Image edge and texture have direction,and there is spatial correlation between the neighbored pixels,so there is the adjacent gray value.In this paper,an algorithm is proposed to improve the ability of fractional differential operator.Firstly,3×3 template is divided into four sub-templates with different directions around the detecting pixel,and then the four weight sum values for the four sub-templates are obtained.Consequently,an enhancing value which is maximum value of the four weight sum values is gained.The experiment results of edge enhancement show that the improve algorithm can enhance edge and texture information effectively more than 5×5 template operators.