虽然有很多关于如何摆弄（拉丁语）刻度标签、刻度位置或刻度颜色的帖子，但我找不到任何关于如何更改刻度本身的长度和宽度的内容（无论是实际示例还是文档）。也许我只是没有找到正确的搜索短语。
无论如何，这个问题可能不需要 MWE，但为了提供一个简单的“演示答案”，这里有一个简单的图，我想将长度（从刻度线顶部到轴的距离）减少（比如说）50%，相对于默认长度。提前谢谢。
\documentclass{article}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}
[width=190pt,axis x line=middle, axis y line=center,
tick align=outside,
xmin=0.3,xmax=7.7,ymin=0.44,ymax=1.05,
xlabel={\emph{x-axis label}},ylabel={\emph{y-axis label}},
xtick={1,2,3,4,5,6,7},ytick={0.5,0.6,0.7,0.8,0.9,1.0},
x label style={at={(axis description cs:0.5,-0.1)},anchor=north},
y label style={at={(axis description cs:-0.1,.5)},rotate=90,anchor=south},
every tick/.style={black,semithick,height=1cm},
ylabel style={yshift=0.2cm}, xlabel style={yshift=-0.2cm}]
\addplot+[mark=none,smooth, thick] plot coordinates {
(1,1)
(2,0.75)
(3,0.666)
(4,0.625)
(5,0.6)
(6,0.5833)
(7,0.571)
};
\addplot [red, dashed, no markers, thick] coordinates {(0.3,0.5) (7.7,0.5)};
\end{axis}
\end{tikzpicture}
\end{document}
答案1
major tick length刻度长度可以通过选项（或别名）配置。小刻度可以通过选项（或）tickwidth配置。在这种情况下，我们只有主刻度。默认值为，可以通过派生而来。我在“4.15.4 刻度微调”一节中找到了选项名称minor tick lengthsubtickwidth0.15cm\pgfkeysvalueof{/pgfplots/major tick length}手动的的pgfplots。
示例，将刻度长度设置为默认值的 50％：
\documentclass{article}
\usepackage{pgfplots}
%\pgfplotsset{compat=1.12}
\begin{document}
\begin{tikzpicture}
\pgfmathsetlengthmacro\MajorTickLength{
\pgfkeysvalueof{/pgfplots/major tick length} * 0.5
}
\begin{axis}[
width=190pt,
axis x line=middle,
axis y line=center,
tick align=outside,
xmin=0.3,
xmax=7.7,
ymin=0.44,
ymax=1.05,
xlabel={\emph{x-axis label}},
ylabel={\emph{y-axis label}},
xtick={1,2,3,4,5,6,7},
ytick={0.5,0.6,0.7,0.8,0.9,1.0},
x label style={
at={(axis description cs:0.5,-0.1)},
anchor=north,
},
y label style={
at={(axis description cs:-0.1,.5)},
rotate=90,
anchor=south,
},
major tick length=\MajorTickLength,
every tick/.style={
black,
semithick,
},
ylabel style={yshift=0.2cm},
xlabel style={yshift=-0.2cm}
]
\addplot+[mark=none,smooth, thick] plot coordinates {
(1,1)
(2,0.75)
(3,0.666)
(4,0.625)
(5,0.6)
(6,0.5833)
(7,0.571)
};
\addplot [red, dashed, no markers, thick] coordinates {(0.3,0.5)
(7.7,0.5)};
\end{axis}
\end{tikzpicture}
\end{document}
粗体刻度数字
这是对 CroCo 的回答评论以及 Manuel Kuehner 博士的评论。
可以通过选项设置粗体刻度数tick label style。由于刻度数默认在数学模式中设置（参见\axisdefaultticklabel），\boldmath因此会获得粗体刻度数。
Keytick label style附加到every tick/.style，因此以下更新的示例（使用pgfplots1.17）合并了两个键：
\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{compat=1.17}
\begin{document}
\begin{tikzpicture}
\pgfmathsetlengthmacro\MajorTickLength{
\pgfkeysvalueof{/pgfplots/major tick length} * 0.5
}
\begin{axis}[
width=190pt,
axis x line=middle,
axis y line=center,
tick align=outside,
xmin=0.3,
xmax=7.7,
ymin=0.44,
ymax=1.05,
xlabel={\emph{x-axis label}},
ylabel={\emph{y-axis label}},
xtick={1,2,3,4,5,6,7},
ytick={0.5,0.6,0.7,0.8,0.9,1.0},
x label style={
at={(axis description cs:0.5,-0.1)},
anchor=north,
},
y label style={
at={(axis description cs:-0.1,.5)},
rotate=90,
anchor=south,
},
major tick length=\MajorTickLength,
ylabel style={yshift=0.2cm},
xlabel style={yshift=-0.2cm},
tick label style={black, semithick, font=\boldmath},
]
\addplot+[mark=none,smooth, thick] plot coordinates {
(1,1)
(2,0.75)
(3,0.666)
(4,0.625)
(5,0.6)
(6,0.5833)
(7,0.571)
};
\addplot [red, dashed, no markers, thick] coordinates {(0.3,0.5)
(7.7,0.5)};
\end{axis}
\end{tikzpicture}
\end{document}
