We need more information. You don't say what the swing is made from. Or is it painted. Power washers work well on most outdoor furniture.

It is made of nylon the material. And its a metal swing.

How about good old soap and water with maybe a little bleach to kill any mold in the fabric. You could always spray paint the metal with Rustoleum if its all rusty.

I have two outdoor swings. When I clean them, I use simple mild soap and water. Last year, One was getting rusted...so I cleaned it and then used Krylon paint. It now looks brand new.
Hope this helps.

CORRECTION....I used Rustoleum. This is great to use on rusty out door furniture.

Hey guys, Heres a picture of my outdoor swing that needed to be cleaned.

Here is a link that might be useful: Outdoor swing

Angel:
I can't see the swing too well, but is mildew your problem? I wash my outdoor painted furnishings (take the cushions off) in a solution of 10% bleach to water. It won't kill the grass or plants or anything if you hose the area down after.
If your furniture is coated with plastic, I was told to use an RV cleaner (I have to use this on my gutters). Works great on the black mold/mildew.

GGG

I give all my metal outdoor stuff a new coat of paint every year or two. This year I also purchased some of the FUSION paint for plastic and I was quite impressed. I heard that they are known to plug up but I think that maybe is if you try to save a partial can (??). Worth the $3.xx at walmart for me anyhow =)

Good luck!
Stacey =)