The idea is that even ss nucleic acids will form sufficient secondary structures to trap sybrgreen or etbr. That said, I read somewhere that sybr green ii is more suitable to the purpose.

Ethium bromide in gel is good for this. Now-a-days SYBR is used in many cases because of its potency towards the process you mentioned.

So far, I can not visualize ssRNA on agarose gel by using both Etbr and SYBRsafe DNA staining. I do isothermal RNA amplification (NASBA method) and then check the result by electrophoresist. NASBA use DMSO and Sorbitol. I think it may cause there are no secondary structure in RNA, thus EtBr and and SYBR safe did not work with me.

I have read about SYBR green II, i agree with you Tarik. I also found another SYBR, SYBR gold. i read this one is also good for ssRNA. 

Thank u Shankhadeep, Tarik, Tyler

Why arnt you going for etbr or acridine orange... SYBR green can be used buy is quite tricky to detect