Hi jackmell,
Thanks a lot! Your suggestion is very valuable to me.
I adjust my DE to
\left(y')^2=a+cy^2+dy^3
with the boundary of
\left y(\infty)=0
and the simplified equation is
\left(y')^2=cy^2+dy^3
By subtitute
\left t=\sqrt{c+dy}
I finally get
\left \frac{adt}{t^2-b}=dx
And its...