h = plot(...) returns a column vector of handles to lineseries graphics objects, one handle per line
其个别代表哪条线, 试试下式并比较下
aa=[1:6];aa=repmat(aa,10,1); hh=plot(aa,'o-'); pause;
set(hh(2),'visible','off'); pause;
set(hh(3),'visible','off'); pause;
set(hh(4),'visible','off');