matlab有自带的plotyy可以画双坐标，但是三坐标的话需要自己添加一层axes，因此搜索之后自己整理出了一个可以任意添加多条y轴的脚本，这里以三轴为范例。

每新建一层axes，便开始画图以及进行图形的设置，通过不断叠加达到画多条线的目的，也可以将bar与line叠加。y轴的范围可以自行调整，但是唯一的bug就是图例的位置是三个图层分别决定的，没法儿做到完美连接。

Code:

%% 画3y轴的figure；

fontsize=24;

axesPosition = [250 100 1100 600]; %# Axes position, in pixels

yWidth = 60;        %# y axes spacing, in pixels

xLimit = [1 10];   %# Range of x values

xOffset = -yWidth*diff(xLimit)/axesPosition(3);

x=[1:10];y1=sin(x);y2=cos(x);y3=tan(x);

%# Create the figure and axes:

% plot 1st data

figure('Units','pixels','Position',[100 100 1500 800]);

h1 = axes('Units','pixels','Position',axesPosition,...

   'Color','w','XColor','k','YColor','r',...

    'XLim',xLimit,'YLim',[-5 5],'NextPlot','add');

plot(h1,x,y1,'-sc','color',[0.7 0.2 0.2],'LineWidth',3);hold on;

legend(h1,'y1','Location','northwest','orientation','horizontal','box','off','Fontname','Times New Roman','FontWeight','bold','FontSize',fontsize);

set(h1,'FontSize',fontsize,'FontName','Times New Roman','FontWeight','bold','ycolor',[0.7 0.2 0.2]);

xlabel(h1,'Num','FontSize',fontsize,'FontName','Times New Roman','FontWeight','bold');

ylabel(h1,'y1','FontSize',fontsize,'FontName','Times New Roman','FontWeight','bold')

% plot 2nd data

h2 = axes('Units','pixels','Position',axesPosition,'yaxislocation','right', ...

   'Color','none','XColor','k','YColor','m', ...

    'XLim',xLimit,'YLim',[-5 5],...

   'XTick',[],'XTickLabel',[],'NextPlot','add');

plot(h2,x,y2,'-oc','color',[0.4 0.5 0.2],'LineWidth',3);hold on;

set(h2,'FontSize',fontsize,'FontName','Times New Roman','FontWeight','bold','ycolor',[0.4 0.5 0.2]);

legend(h2,'y2','Location','north','orientation','horizontal','box','off','Fontname','Times New Roman','FontWeight','bold','FontSize',fontsize);

ylabel(h2,'y2','FontSize',fontsize,'FontName','Times New Roman','FontWeight','bold')

% plot 3rd data

h3 = axes('Units','pixels','Position',axesPosition+yWidth.*[-2 0 2 0],...

   'Color','none','XColor','k','YColor','b',...

    'XLim',xLimit+[2*xOffset 0],'YLim',[-5 5],...

   'XTick',[],'XTickLabel',[],'NextPlot','add');

plot(h3,x,y3,'-oc','color',[0.3 0.5 0.7],'LineWidth',3);hold on

legend(h3,'y3','Location','northeast','orientation','horizontal','box','off','Fontname','Times New Roman','FontWeight','bold','FontSize',fontsize);

set(h3,'FontSize',fontsize,'FontName','Times New Roman','FontWeight','bold','ycolor',[0.3 0.5 0.7]);

ylabel(h3,'y3','FontSize',fontsize,'FontName','Times New Roman','FontWeight','bold')