as follows fig1 shows the control method for sma in the invention five control devices 101 are provided firstly the shape memory alloy 102 is divided into 5 sections having the same length at about 20 cm there are connected to respective 5 control devices 101 thus the mutual distance among control devices 101 each other is the same the constant current supply device 103 is connected to the shape memory alloy 102 to provide about 100 ma of constant current after the current passes through the shape memory alloy 102 from the constant current supply device 103 five control devices 101 can control the elongation amount of the shape memory alloy 102 the control method of the invention can reach about 15 of the elongation amount and it is nearly a linear way and can get sectional control effect of sma the sectional system will change sma in order to avoid the different flex speed of the system and protect the sma so 100 ma of constant current supply is used the power consumed and the heat generated by sma will be the same the invention can adjust the number of control device 101 when the control device 101 is increased or decreased the same flex amount still can be controlled fig2 shows the schematic diagram for the control apparatus of sma of the invention comprising a battery power device i e constant current supply 201 to provide constant current supply and boost current and a charge pump 202 sets up from the first voltage as 1 5v to the second voltage as 4 5v the main controller 203 is a 8 bit controller 12c2052ad having a d transformation function which can input or output a specific current as 20 ma the light sensitive resistor cds.