Spacing problem at List of Figures

Loading the tocloft package and using the macro \cftsetindents for figure and table items should do the job. Specifically, you could add the following code to your document's preamble:

\usepackage[titles]{tocloft}
\cftsetindents{figure}{0em}{3.5em}
\cftsetindents{table}{0em}{3.5em}

The second \cftsetindents instruction, i.e., the resetting of the indentation amount for the entries in the List of Tables, isn't strictly necessary for your document. However, doing so may be appropriate to keep the appearance of the List of Tables in sync with that of the List of Figures.

You're of course free to adjust the indentation amount (3.5em) to suit your preferences.

You can load package tocbasic and use the automatic number width feature for figure or table entries:

\usepackage{tocbasic}
\DeclareTOCStyleEntry[dynnumwidth]{tocline}{figure}% for figure entries
\DeclareTOCStyleEntry[dynnumwidth]{tocline}{table}% for table entries

A complete example to show this, would be:

\documentclass{report}

\usepackage{tocbasic}
\DeclareTOCStyleEntry[dynnumwidth]{tocline}{figure}

\usepackage{caption}% only to have \captionof for the example

\begin{document}
\listoffigures

\chapter{Generation of dummy entries to the list of figures}
\makeatletter
\@whilenum\value{figure}<200\do{%
  \captionof{figure}{This is test figure \thefigure}
}
\makeatother
\end{document}

You need at least three LaTeX runs to get the correct number width:

You can find more information about package tocbasic, \DeclareTOCStyleEntry, style tocline and option dynnumwidth in the KOMA-Script manual, scrguien.pdf (English) or scrguide.pdf (German).

But if you want you can also change the number width manual using option numwidth, e.g.

\usepackage{tocbasic}
\DeclareTOCStyleEntry[numwidth=3.5em]{tocline}{figure}% for figure entries
\DeclareTOCStyleEntry[numwidth=3.5em]{tocline}{table}% for table entries

Both solutions can be used with every standard class and does also work with several other classes.

If you are already using a KOMA-Script class, you can use the same solution without loading package tocbasic, because these classes already load the package. But with KOMA-Script classes you can also add class option listof=flat:

\documentclass[listof=flat]{scrbook}

\begin{document}
\listoffigures

\chapter{Generation of dummy entries to the list of figures}
\makeatletter
\@whilenum\value{figure}<200\do{%
  \captionof{figure}{This is test figure \thefigure}
}
\makeatother
\end{document}