74hc595 without connecting the pic also, the output leds to the 595 is always on, the connection diagram is as below
when i touch the pins of 595, the output pins on and off irregularly

what canbe the problem?

connection diagram as below

 

Unconnected inputs can cause erratic behavior. Lack of bypass can also cause it.

 

which all input to be connected still?
Bypass means Bypass capacitor??

 

You said that you were testing the 74HC595 without connecting the PIC. You tell me which pins on the 74HC595 are not connected to any driving source. I meant to say "bypass capacitors", you are correct.

 

yes, only VCC and gnd were connected, all others unconnected

 

And those floating inputs are high impedance which means they can assume any value without drawing or supplying any significant current. Floating pins on a CMOS devices implies erratic operation. Why does this surprise you?