p_cor.order + scale_fill_gradient(name="Value", low = "white",high = "red") +

theme(axis.text.x = element_text(vjust = 0.5, hjust = 0.5, angle = 90))+

coord_fixed(ratio=1)+

theme(axis.text= element_text(size = 8,family="ARL"))+

theme(plot.margin = unit(c(0.1,0,0,0), unit="mm"))+

labs(x = "Var1", y = "Var2", title = "correlation")+

theme(plot.title = element_text(size = 13,hjust = 0.5,family = "ARL" ))+

theme(legend.key.width=unit(3,'mm'),legend.key.height=unit(3,'cm'))+

theme(legend.title = element_text(size = 8))+

geom_text(aes(Var1, Var2, label = value), color = "black", size = 3)

跑一下代码，出来的图就是这样的