A microfluidic chip production method which can copy an arbitrary factions in an existing chip is presented.It can be used for repairing and integration of existing chips in laboratory.The structure is extracted by a window method which may exclude adjacent structures interfere with the extracting chip to keep the surface of new chip smooth and tidy.It is particularly applicable to replica molding the special micro-structure and three-dimensional structure of chips which the current soft-lithography replication process could not realized yet.The PDMS chip produced in the experiment has a 30 μm-long 5 μm-wide

5 μm-deep channel.Observed under the microscope

the surface is smooth

the nature of window-channel sound reproduction

the edge between the window and the surface apparents a sudden change.