Abstract: The effective fracture permeability and fracturing scale which are allowed by the economy is rarely considered in the
present fracture design method，as a result，the long effectiveness and economics of the fracturing results can not be ensured.
Based on the concept of Proppant Index，with maximization of economy profit as the objective，an optimal proppant index
function is established by considering the relationship between economic aspects，reservoir size and fracturing scale. For a
given reservoir size the only optimal proppant index and optimal fracture length can be determined by using this function，and
with the iteration method we can get the optimal fracture parameters under non-Darcy flow conditions. The results show that the
more severe non-Darcy flow effect in the fracture，the smaller the optimal proppant index and fracture length is，and the larger
the optimal fracture width is，a fracture with lower penetration ration and higher fracture conductivity is needed to minimize
the non-Darcy flow effect.

Key words: non-Darcy flow, fracturing, optimal design, optimal proppant index, effective permeability