components of wave trap

In my design, I want to filter the signal of 10 KHz.How to design a wavetrap? And the bandwidth must be narrow.

This can be done by an active notch filter ..
Take a look at the attached picture ..
The beauty of this circuit lays in its simplicity ..
Basically it is a combination of variable low-pass and a high-pass filters and you can independently adjust the frequencies, so the stop-band can be quite narrow ..
http://www.zen22142.zen.co.uk/Circuits/Audio/notch.htm
Regards,
IanP

Thanks. But the schematic is complicated. I need a passive wavetrap with few components.

In this case try this passive twin-T notch filter:
Quoted from:
"Filters"
http://www.du.edu/~etuttle/electron/elect15.htm

Regards,
IanP

In this schematic, there is a large insertion loss. The signal will become weak.

That is true, but you can easily add a single stage amplifier before and a buffer after (or the opposite way around) this notch filter to compensate for its loses ..
Something like LM358 (dual opamp) should do ..

Regards,
IanP