Hello 萧佳茗, I am also a student, here is what I could come up with your question,

The distinction between the various types of monetary policy lies primarily with the set of instruments and target variables that are used by the monetary authority to achieve their goals.

Monetary Policy:                Target Market Variable:                        Long Term Objective:
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Inflation Targeting        Interest rate on overnight debt        A given rate of change in the CPI
Price Level Targeting        Interest rate on overnight debt        A specific CPI number
Monetary Aggregates        The growth in money supply                A given rate of change in the CPI
Fixed Exchange Rate        The spot price of the currency        The spot price of the currency
Gold Standard                The spot price of gold                        Low inflation as measured by the gold price
Mixed Policy                 Usually interest rates                        Usually unemployment + CPI change
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The different types of policy are also called monetary regimes, in parallel to exchange-rate regimes. A fixed exchange rate is also an exchange-rate regime; The Gold standard results in a relatively fixed regime towards the currency of other countries on the gold standard and a floating regime towards those that are not. Targeting inflation, the price level or other monetary aggregates implies floating exchange rate unless the management of the relevant foreign currencies is tracking exactly the same variables (such as a harmonized consumer price index).

Inflation targeting
Under this policy approach the target is to keep inflation, under a particular definition such as Consumer Price Index, within a desired range.

Price level targeting
Price level targeting is a monetary policy that is similar to inflation targeting except that CPI growth in one year over or under the long term price level target is offset in subsequent years such that a targeted price-level is reached over time, e.g. five years, giving more certainty about future price increases to consumers. Under inflation targeting what happened in the immediate past years is not taken into account or adjusted for in the current and future years.

Monetary aggregates
In the 1980s, several countries used an approach based on a constant growth in the money supply. This approach was refined to include different classes of money and credit (M0, M1 etc.). In the US this approach to monetary policy was discontinued with the selection of Alan Greenspan as Fed Chairman.
This approach is also sometimes called monetarism.

Fixed exchange rate
This policy is based on maintaining a fixed exchange rate with a foreign currency. There are varying degrees of fixed exchange rates, which can be ranked in relation to how rigid the fixed exchange rate is with the anchor nation.

Gold standard
The gold standard is a system under which the price of the national currency is measured in units of gold bars and is kept constant by the government's promise to buy or sell gold at a fixed price in terms of the base currency. The gold standard might be regarded as a special case of "fixed exchange rate" policy, or as a special type of commodity price level targeting.

For your professor's request, target market variable and long term objective are your potential criteria.
I hope this helps.
Thanks.

谢谢大侠，您看我理解的对不对阿，您的意思是货币政策的划分主要是对他长期目标以及货币政策工的使用来划分的。
我做实证研究，需要划分货币政策，意思就是这段时期是紧缩期还是宽松期，需要根据什么来划分？文献中使用比较多的是：货币政策执行报告，货币政策感受指数，货币政策偏紧指数，MP=M2增长率-GDP增长率-CPI增长率。我疑惑的是我到底应该根据什么来划分，货币政策可以划分为紧缩型和宽松型，这样一刀切对么？我最近想不清楚这些问题了